- Error message after you upgrade a computer that uses a processor other than an Intel processor to Windows XP Service Pack 2 or to Windows XP Service Pack 3: "STOP: 0x0000007E"
http://support.microsoft.com/kb/953356
The short version is that if you run WSUS on an HP/Compaq computer running XP SP0/SP1 on an AMD processor, you'll get a STOP 0x7E. So if you run the factory recovery on said system, and then run WSUS, you'll get stuck in a reboot loop. It's easy enough to fix (see the above KB), but it costs time and kills the automatic update process.
I don't imagine it would be very hard to add a check in WSUS for this prerequisite update, and I could certainly hack it in there myself given the time to read through the sources. But if someone with more of that "Free Time" I keep hearing about wanted to tackle it, I'd be mighty appreciative.