XP won’t install after CPU upgrade

I have WinXP pro, and I had it installed to my AMD 1800+, SB live value, geforce4 4400 Asus A7V333 and when I upgraded my CPU to a 2400+ WinXP would only boot to the last splash screen and give a 7b stop error after sitting for an hour or so. I tryed a fresh install with the same problem and I even bought a new WD 60gig and tryed the install with the same problem. I took out the SB live value card during these installs. I reinstalled WinME and it’s running fine. But I hate having bought a full version of WinXP and can’t use it. I’ve called Microsoft’s tech support without solving the problem.
Thanks for any help,
Pete