Installing windows to bootcamp: "error loading operating system"

It doesn't matter whether I'm trying to install windows 7 or XP sp2 or XP sp3. I get the same Error. I've tried different CDs for each flavor too. (I believe in backup!) These are NOT bootlegged so that is not the issue.

I have a 1.66MHz Macmini core duo with 2GB RAM, 250GB HD, running 10.6.8 Snow Leopard. The Superdrive seems to work as I was able to burn an ISO to CD earlier today with no problems. I don't know what else to check.

Has anyone else had this problem? or maybe have any ideas of what I can try further? Any help would be appreciated. I usually don't need windows, but my Will software is PC and I need to update my paperwork.

Thanks,

Kayo