Well.. first of all you should definitely say what you would really need in a laptop:
- portability?
- low weigth?
- big screen?
- very long usage during the day? (8hrs/day)
- brand preference?
- buy online? buy locally? where?
budget under $400 is quite low but something should come out anyway
Then go to the nearest store you have, take down a list of all the models you think could be worth the money they cost. Plus one or two you think are "a little" too expensive.
After this, come back and say us which are the models you are interested so we can help you build a comparison. ;)
Check out a HP G60 $320-400 or search for your preffered brand on Amazon I found a few Thinkpads used and new within the specified price range. Have fun choosing a laptop.