well, regardless of how he got it, vista is rough enough with 32bit. i'm already beta testing 32bit...i wouldn't go fucking around with 64bit, i heard drivers are very hard to come by for a lot of things.
just a heads up
oh, and since i trust computer techs about as much as mechanics (sorry dolphin) make sure you get back that "bad" ram.
i've found that when ram is bad, the comp doesn't even boot. if you know for sure your BIOS was fucked, then the bad ram thing might sound like a sale rather than a repair. keep the ram, RMA it, or at least get a second opinion on it. if it's bad, cool. if not, throw a fucking rock through their glass door.