I have been playing with PuppyLinux on an old banger PC, pleased because it runs like a rocket, compared to WinME it came with. Still learning my way around the system. You can run it from a stick or single cd, but you do, as previously said, need spare disc space to store your personal settings and that. Ideal for beginner like myself. Although it I have not ran it from within windows, it can read all the hard discs, so you can still access your windows My Docs, My Music etc.