A repair install is usually the trick to this with both XP and 7, but Vista doesn't really have that option. Otherwise you can switch to the generic mass storage driver before switching to the new motherboard. Of course, when the existing motherboard won't stay on for more than a few seconds, this doesn't really work.

Although neither of those drivers were what I needed.

And you can run regedit from the Vista recovery boot option once you pick command prompt.

Since the new board had an nVidia chipset, the driver that I had to enable (switch the "Start" value to 0) was nvstor. I suppose you could just enable anything with 'ahci' and 'ide' in the name if you didn't know what driver it was supposed to use.

Anyway, my flat $50 labor fee isn't going to amount to much per hour this time. But you don't get this kind of service from the Geek Squad.