Emacs -- I am sure you know that there's Carbon Emacs (thanks to Alex Choi -- http://members.shaw.ca/akochoi-emacs/).

Multi-protocl chat: you can choose between Adium [http://www.adiumx.com] (with a bit strange take at some idelogical issues, but free, at least for now) or Fire [http://fire.sf.net/].

Multiple dasktops: aside from comercial app you mentioned, you could also use free (both meanings) one -- DesktopManager [http://wsmanager.sourceforge.net/]

Naturally, you can go on and use your beloved X apps within X11, since it happily runs on an Apple :)

On OOo: while you can use MacOS X X11 version of it, I prefer NeoOffice/J's Java version.

Just got a PowerBook G4 1.5 GHz. Great OS, great apps, but caveats include: slow processor (compared to Intel and now even iMacs), incredible heat (bottom gets WICKED hot after short period of time), and some Java trade-offs.

Let me expound on the Java stuff. I like the JVM's nice tight integration with OS resulting in fast startups and lower overall memory usage, but I wish I could use some third-party VMs. Apple's done a great job integrating their JRE with the native platform, but there's no server VM! Server VM performs *much* better than client in many situations. Apple is closely tracking Java 5, but you can't get Java 5 pre-releases without paying a bundle. Java apps designed for OS X look beautiful and almost seem native, but many cross-platform Java apps (like IntelliJ IDEA) run noticably slower and with more bugs than on Sun JVMs.

But on the other hand, remote controlling the laptop during prezos with my bluetooth phone using Salling Clicker is almost worth the price of admission alone -- very cool.

Whilst Emacs on Mac OS X works quite well it doesn't work as well as Emacs on linux or Solaris (hey, why is Solaris missing from the list of operating systems?).

If you don't use any network connections from within Emacs then the Mac is probably fine. If you need them then things get a bit messy (can't C-g out of many situations due to the way that the event loop is implemented).

That said, the Powerbook is much nicer hardware than any PC laptop I've owned (including a Tecra 8200).

Be sure if you choose Linux on a laptop that the wireless hardware is supported as you will require. I know smart technical folks at the office have trouble with this on their ThinkPads. My officemate has given up I believe and runs Windows and uses X11 remote display from a workstation to work. Mac, though "officially unsupported" works great for me. I just added the appropriate wireless hardware to my 3.5 year old Mac PowerBook G4 and it all has "just worked" wonderfully.

Regarding your needs, I've been happy using VirtualDesktop (six screens). (I use CDE at work on AIX, 8 screens on each of two monitors -- so, you can see I love my virtual screens. ;-)

I like Fire.app for multi-protocol IM. I use it for IRC and it's acceptable, but other clients might be better. There's a new app called Be sure if you choose Linux on a laptop that the wireless hardware is supported as you will require. I know smart technical folks at the office have trouble with this on their ThinkPads. My officemate has given up I believe and runs Windows and uses X11 remote display from a workstation to work. Mac, though "officially unsupported" works great for me. I just added the appropriate wireless hardware to my 3.5 year old Mac PowerBook G4 and it all has "just worked" wonderfully.

Regarding your needs, I've been happy using VirtualDesktop (six screens). (I use CDE at work on AIX, 8 screens on each of two monitors -- so, you can see I love my virtual screens. ;-)

I like Fire.app for multi-protocol IM. I use it for IRC occasionally and it's acceptable, but there are probably better clients. I just heard of a new IRC client app called Conversation that looks promising and I intend to check it out.

Fink is good for convenient install of some Unix apps, like ImageMagick, tetex. I used to use it for gimp, but a Gimp.app drag-and-drop install is much simpler.

And OS X gives you the option of using OmniGraffle which I really like (*huge* improvement over what I was able to accomplish with xfig).

With print-to-pdf built-in and well supported in just about everything including tetex via Fink, I really like a PDF work flow when doing document construction. I worked out how we wanted to setup a DocBook documentation system at work first on my Mac laptop -- hey, thanks for your contributions in that area! -- and then we put it on a Linux machine for everyone to use.

I don't think you'll go wrong either way. There'll be some compromise either way. Just wanted to share my experiences in case you choose OS X.

Crickey, look at that. Sorry about the half in-complete post which precedes the full comment. I hit Submit rather than Preview. Feel free to edit to remove the error and delete this followup if you are so inclined.

I have been relatively unhappy with Emacs on OS X. The latest packaged Carbon binary has weird issues (interactive search backwards hangs for no reason) and crashes often with no perceptible pattern. You might have more luck compiling it yourself from CVS.

Firefox on OS X is similarly second-class. Many extensions do not work properly (tabbrowser) and overall it feels sluggish compared to Firefox on comparable hardware running Windows or Linux.

Fink is wonderful, and FinkCommander is a good GUI frontend for it. If you like living on the edge, you can try Gentoo OS X (Gentoo's Portage system to install additional apps within OS X), but that is quite new and may not gain much traction.

Overall you'll probably be happier with a Linux laptop. Watch out for the Thinkpads! Or anything else with an unsupported wireless card. Research http://www.linux-laptop.net/ for details.

Norm - your sorting hat doesn't work - as all of the apps you mention you can get to work quite well on just about any platform! I'm in a similar situation, though currently running on a dual G5 and don't really want to leave OS X world, but will probably have to due to d).

I think you are going to have to add additional criteria. a) Maybe "ease of use" - do you want things to "just work" all the time? b) "Fun Factor", community, productivity, apps, utilities c) Do you always want "bleeding edge" - ie. Java 5.0 beta now? and d) Power (GHz). How much do you want and need?

[On a) and b), I think Powerbook wins hands down. For c), it doesn't. For d) it doesn't ]

And for you Emacs people - I used to have problems with Emacs on OS X. I then downloaded the latest source straight from the CVS, compiled, and now it's much much better.

I'd have thought 1.5Ghz would be pretty sporty, but a couple of folks have suggested that that's slower than 1.5Ghz on x86. Dunno what to think about that.

On the other hand, I just spent half an hour wrestling with the Firewire stack on this box. I had to reboot twice. Rebooting is for hardware upgrades, damn it. So I'm in a sour mood at the moment. All so I could get my new Pogues CD onto my iPod, for what it's worth.

But they're going to make me pay money for OS upgrades. What's up with that?

I still don't know.

Do like me. Get a Mac, install both Linux and OS X and switch between them when you feel like it.

I think it's fair to say that your *nix-originated apps such as emacs, gimp, etc don't run quite as well on MacOS X as they do on Linux. Either the Aqua port lags behind the main development, or you run it as an X app, where it is not quite as integrated with the rest of the OS. I find the carbonized emacs to be quite acceptable.

The main advantage with OS X is the new types of apps that you may not have encountered before on other OSs. Like the iLife suite and SubEthaEdit you mentioned. But there are more. I don't know how I lived without Quicksilver. And seriously, give Expose a try before you install a virtual desktop manager.

The yearly upgrade fee is generally worth the cost in my experience, but YMMV.

Forgot to mention: my emacs was compiled from CVS.

And seeing as noone else has mentioned it, allow me to include a quick plug for darwinports (darwinports.opendarwin.org) which will get the latest emacs from the CVS repository, compile and install it all with a single

sudo port install emacs +carbon

Another way to think about it is:

"It's not the Apps, it's what you want to accomplish".

Mark Pilgrim wrote:

"Watch out for the Thinkpads!"

I've heard that Thinkpads can work well with Suse.

There even are certified/supported combinations, check eg http://www.suse.com/en/business/certifications/certified_hardware/sl91.html

In Germany, nofost.de offers Thinkpads with a Suse installation CD for Thinkpads; I don't know if Suse (respectively Novell) sells those in the US.

I've got a 17" PowerBook with 1.5G CPU and mere 512Mb RAM and I can't call it slow, though YMMV. It sure is faster than my T30 with 768Mb and a 1.8G P4M running W2K!

Emacs — I'll second CVS checkout and a compile, nver known that a binary has been out there, actually. I will also concur that it is not as good as X11 one (but the same, if not more, is true for a Win32 one), but it works. My biggest problme with it was to get it to properly handle Unicode — much hassle with fonts, etc.

And if you do go for a ThinkPad with Linux — I'll second the WiFi comment, and add the Winmodem one: you may be better off plugingn PCMCIA card for a modem instead of trying to get Linmodem to work, at least in my experience...

P.S. Just noticed that HTML tags were added to comments! Cools :)