Before you buy, what are you going to be using it for?
Are you going to carry it around everywhere? Or is it a stay-home laptop?
If you plan to take it out a lot, I would suggest getting a lighter laptop.
Definately wait to get the new Asus EEE, it weighs only 2 lb and it is priced around $400:
Asus Eee PC 900 - TrustedReviews