OK, I bought my new parts for Computer 1, and successfully installed them into the computer. This is a big deal for me, its my first build/upgrade. I turned the computer on and it booted up XP. No need for a repair, everything started up as normal, albiet with the occasional screen flicker, video driver problem.
Upon logging in, it told me I had 3 days to activate Windows XP. Fearing the worst and rehearsing my story in my mind, I rang the Microsoft number. I thought I'd just try the normal phone activation thing (enter a 56 number code, they give you a 35 number code) and it worked right off the bat.
It really was outrageously simple.