I installed a copy of Windows 7 Ultimate (which turned out to be pirated) on my (Toshiba Satellite) Vista Home Premium laptop. I would now like to go back to Vista, but the CD Key has rubbed off the bottom. Is it possible to retrieve it?
No - the default install uses a special image that dosen't have the key that's at the bottom actually in the system, relying on a key thats in bios, and a standard restore image, so even if you had the original install, you can't get the key off that.
Your only option is to snag a restore disk for the same model, or possibly the same OEM (which won't need the key). If you wanted to use the key at the bottom, you'd have to use it with a generic OEM install disk