I'll admit it, I screwed up. I locked myself out of my own Windows installations. Suffice to say, I had to reinstall BOTH Windows XP and Vista, and activate them again. They activated, but not without going through needless hoops over the phone with Microsoft. Windows XP was particularly troublesome, as I changed the VM settings in Parallels to use 2 processors instead of 1... apparently that irked the activation scheme. ARRRGH! Why does activation have to be such a pain? At least I learned not to deactivate the Administrator account when logged in as the Administrator account. D'oh!