Many new computers come with a satisfaction policy that says a buyer can return it for almost any reason after a short trial period. HP, Dell, and others have been known to sell these returned systems, often called refurbished computers, for 20 percent off their original sticker price. The downside is that these computers often come with only a 90-or-so-day warranty--about 9 months shy of the one-year industry-standard warranty on new laptops. On the whole, I've heard from more people who have had good experiences with refurbished PCs than bad. That said, I'd be wary of a used notebook selling on Craigslist.org or from an anonymous online merchant. Laptops are expensive, and I think that peace-of-mind is worth the extra money you'll spend buying from a trusted business.