That being said, I know I'm going to need a new laptop VERY SOON.
My current laptop overheats like a *bleep* to the point you can literally burn yourself if you touch it the wrong way. (hmm...i've had similar experiences with relationships).
Also it's just as slow as anything and probably needed an upgrade a year ago.
I use xp right now, which I like. It's simple to use, not like vista was. I haven't had enough experience with Windows 7 to judge yet. And I've always liked the look of macs. They just seem like they work when you want them to.
Hopefully something you've used, and hopefully something that can handle the stress an IM puts on it everyday.