I say go for the iBook. Barring that, get a Thinkpad.
Every other brand name is just about equal, it seems. Dell used to be a bit above the rest, but more and more I hear that they’re not that special anymore.
I heartily reccomend eMachines laptops. Mine has been very reliable. My ex-girlfriend’s even survived having water dumped on it while turned on. All I did was take it apart, let it dry, and it booted back up. Mine has only had one major problem in a few years, and eMachines support line was very very helpful, and I had the new part the next day via FedEx. Not saying they never break, everything does, but they have excellent support when they do.
(corrected by me)
I have a 700m and I love it. It’s LITERALLY about the size of a notebook (though a bit thicker, of course), and weighs less than 5 pounds. The screen is amazingly bright and easy to keep clean, and it’s also more of a “widescreen” format, which is cool. It does have an integrated graphics card which can’t handle the latest and greatest games, but if that’s not a problem, there you go.
Also, you should be aware that starting tomorrow (Thursday) morning, Dell is offering a coupon code for $750 off $1500 notebooks (note: this is not a referral link). Might be a way to extend your notebook-purchasing dollar.
Well I bought a laptop today!
It was down to the IBM Thinkpad or a Dell. I configured multiple systems and such. I decided to go with the Dell, because I could get a much better setup than the IBM for about half the price (thanks to the link from Garfield226:)) I saved a assload of money on a Inspiron 6000!!
It is suposed to be delivered around March 3 or so. I am so excited I can hardly stand it. I am such a dork. 
Wow, with that kind of turnaround time, I would have gone with the Thinkpad! Your laptop will be obsolete by the time you get it.
I meant May 3rd…
You mean 600m, right? I’ve got one and I like it quite a lot, but I wish I had a bigger hard drive (only 60gig). Here’s a tip for you, though:
There’s a bit of blue plastic that runs along the bottom of the keyboard, and there’s a seam/joint with the main body piece. If you get a piece of grit stuck in the seam and close the lid, you could scratch your screen like I did. It also just kind of rubs the screen in a nasty way. So I put electrical tape along the seam. Works great.