well the thing is with him is:
he doesnt play games, he doesnt kniw 1 thing about computers so he cant overclock and when i suggested it to him he started throwing wild stories of ppls computers blowing up. The stuck with agp part wont bother him since he wont play game at all. and if i get him a s939 pci express or if i get him a 3400+ s754 then it goes over his budget. The proces that i liosted didnt include s&h or taxes.
also he buy new computers when ever a new generation od cpus come out. I even told him to just buy a new cpu becuase he already currently has a Intel p4 2.4B, but he wont listen he wants new everything except the vid card.
I knew a few cases like that. Had to sit them down and ask then what do you want to upgrade? what do you want faster. blah blah, etc. Anyway, he sounds as if he's going to waste his money if he does upgrade. i think you should convince him to hold off, and check his pc for spyware if he's complaining about slowdown. he may want it an amd64, but does he even know what benefits he'll get from one? He doesn't know anything about pcs, does he really need speed he's not going to use? confer with him, and if he absolutely must upgrade, see if you can convince him to go for the lowest amd64. why bother with speed if you're not using it?
looking at your system spec and going along with the "he knows nothing" bit - get him xp home. Sure it seems like a waste, but he's not going to use any new/extra functionality anyway.
edit: about the linux comment - while some guys at college use linux, the colleges i know, dont use it. They use windows, or net bsd, and a few use osx, though my college only used it in the library which wasn't bad.