Vista Home is problematic if you don't do it right.
Do a quick search of this forum to find any post by StormJumper. Appended to his signature are links to instructions on how to do a clean un-install and re-install in Vista... follow those instructions EXACTLY!
Make sure Fab is set up in compatible mode 'XP service pack 2'
You shud be OK at this point to enter the keys (That may be covered in the instructions, I haven't read them as I'm running XP)