Fernando, I do indeed have a valid cd key. It is the one i've been using on my old system that broke. Just waiting to be able to use it on my upgraded machine. Will a xp pro UPGRADE cd be just as suitable as a regular install disc? I'm under the impression they're relatively the same thing. I'll be trying to get a clean OS on ebay in the meantime for a reasonable price. I realize your thread is not about changing to ahci mode after installing xp, but, if you know a link to a solid thread regarding that issue, i would really appreciate you pointing me in that direction. Might as well weigh all my options right? Thanks for the reply, Brian P.S. Props on this thread staying alive for all this time. Simply amazing!!!