Woe is me.I discovered that the Mac store had installed the latest version of BootCamp, which is not compatible with XP, so rather than try to roll back and incur who knows what grief in the process, I downloaded and installed the $80 XP-compatible Parallels 10, only to have my product key rejected when I tried to install XP. I had an OEM license from an old Dell and I guess I used it up when I installed XP on this computer the first time. Doh! Chatted with Microsoft and got the "sorry, we no longer support" line, despite reading that some people have been able to get a new key from them for as little as $10. I would install Windows 7 but the software I am wanting to use (accounting and expensive design software are not compatible). Grrrr.