Probably the easier way to get all that done (though you would have to lose all of the files u needed unless you backed them up BEFORE putting the new hardware in) would have been a full format and re-install of XP. When you install XP, it practically designates itself to that Motherboard and processor specifically. I had the same problem too. formatted, re-installed, and it booted fine. When you did the repair and got kicked out, that was probably because something about the previous install was basically telling Windows Installer "....no"