I’ve got a MBP, which is pretty nice. I almost bought a lenovo thinkpad T61, and what did it for me was really just battery life and aesthetics – the thinkpad not only had a shorter battery life, but the battery stuck out the back and made an ugly wedge shape. If you are still weighing this question, definitely wait on it as long as possible and do some research on upcoming mac products (if that’s even possible :-)...) Here’s a good place to start:
http://buyersguide.macrumors.com/
Also, since there are so many PC’s, I don’t think you should be limiting yourself to Dell or HP – check out this site for reviews, new releases, etc.:
http://www.notebookreview.com/