Vista crashing

I have a Vista PC here, the power supply died and took the motherboard with it. So I installed a new PSU and new MB. Unfortunately, an exact match for the MB was not financially feasible, so I got one with an identical chipset (Nvidia 6150/430). I did one of these exact same rebuilds 2 days ago on a Vista PC using this same MB and it booted no problem. But on this rebuild, the PC crashes to a vague "0x0000007B" blue screen. I have tried the various repair options via the F8 menu and from a Vista install disc w/o any luck. I'm pretty sure the crashing is due to a driver conflict between the old OS being configured for a different motherboard. I guess the question is this: is it possible to remove and/or replace drivers via Recovery Console or a boot CD (like Barts)? The client really does not want to lose any programs; I could simply save any docs, pics, music, etc and reload a clean OS, but she'd lose all her programs (and why does NOBODY seem to have Office install discs or product keys but they all have a fully functional Office installed before the PC/HD dies?).