Check what kind of ram the laptops will be taking. I got a really cheap Compaq laptop for like $300. Had 512 mb ram, 2 ghz amd64 processor, and an 80 gig hdd. The reason it was so cheap is because I chose the lowest amount of ram they would let me get. For every gig of ram added, they wanted $100!
So I get my laptop, go to newegg, look up the ram, and find a pack with 2 2gb sticks (4 gigs of ram total) for under $30 with free shipping. Hmm, $400 for ram, or $30? Tough choice, huh?
Definitely do your own upgrades, you'll save a ton of money and be able to build a much more powerful machine!