Don't buy a full version though. You still have the right and the ability to perform a clean installation with an upgrade copy (of retail status) by inserting the ME CD for examination during the XP installation procedure.
That is; if you have either a retail or OEM copy of ME. Any full copy of a valid OS is permitted under the EULA, even if it is OEM. The use of a retail upgrade copy of XP will effectively turn an original OEM licence into a full retail licence. I clarified this with Microsoft UK recently.
This thread is now locked and can not be replied to.