LOL. congrats. For something similar, I upgraded my uncle and aunts computer running a old celeron 600 (castrated p3 chip) with 256 MB with memory and win 95. Gave them an old skt 939 opteron 165 (dual core) I had laying around. Built them the system and OC'd it to 3Ghz with 2GB of DDR and windows 7. To them it was like night and day. I even tossed in an ati 4850 1GB card along with some games so they could play and try those out.
The rest of my family knows I am a computer guy, but thinks I am weird for having all the constant hardware upgrades but I think I got my uncle at least convinced. Or at least he's now hooked on a few games 🙂