for the first problem, download and update all service packs for XP and office, office (depending on the version) is up to SP4, I think Xp has SP1 out.
check the specs on your MB, it might not be able to read or see a 512 mb stick, also alot of bords are limited to 512, check the manual that will tell you what you need to know.
could also be a dead stick.....
good luck!