Windows XP Embedded (XPe) Is a componentised version of windows xp sp1. You can choose what components you want in XP, Networking, FAT Support, NTFS Support, and theres like 1000 components to choose from. Basicly You can make your OWN personal version of windows xp. This XPe contains a component that redirects all IO calls to the HD to the RAM. Thus it can be booted off a cd. Hope it helps, Chris.