PC World: "Microsoft expects you to pay close to $200 to upgrade your Xbox 360's hard drive from 20GB to 120GB. That's about $150 more than a 120GB SATA drive actually costs. But with this slightly tricky hack, you can save a bundle while boosting your game console's storage capacity to hold more music, video, and other media files.
You'll need a DOS installation on a writable flash thumb drive for this hack. (The utility doesn't work under Windows, and you'll also be disconnecting your PC's hard drive.) First, grab a spare USB thumb drive and copy the HP Drive Key Boot Utility to it. The utility is designed for HP flash drives, but it works on other types of flash drives, too. Also download and mount a DOS image file."