IBM isn't in the laptop business anymore, they sold to the Chinese company Lenovo a while back. Still top notch computers but the price has come down some with the sale.
The Compaq I'm typing this on is a desktop replacement for me, AMD64 2400, half a gig of memory, 40G HD, 15" screen. About $500 with rebates. I like the briteview-type screens but they can have problems with reflections so if you're going to be working someplace bright with it I'd be wary. Also get a bigger, faster HD to start with than the basic version, you'll need more space and a faster HD sooner or later. A DVD burner might be good too depending on whether you think you'll ever burn DVDs with it. If you're going to take it places often spend the extra money to get a lighter & thinner notebook, you'll appreciate it later.
As far as brands, Dell is hard to beat for value - watch techbargains.com and some of the other deal sites for deals. I like Acers too, good value for the money. My Compaq has been stone cold reliable but the external power supply failed; they overnighted me a new one so I can't really complain.
Scott