You won't find a low-priced notebook with a 64-bit version of Vista on it.
I usually go here
to make and look for laptop deal posts. Usually, anything posted by "Deals" autoposter is not really that great of a deal. Mostly the best deals come from the members.
Your best bet is to keep an eye on office store circulars. Office Depot and Circuit City regularly run laptop specials every other week. Just go to their site and look at their "weekly specials" or "circular" ads. Also, price out a Dell Vostro. You can build a very nice gaming laptop for under $800.