I'm running 32bit ultimate on 2x8700MGT's SLi'd (Dell m1730) and am getting the same problem, however, not in WoW. It only occurs in CoD4 and does not BSoD my laptop. Slight pause followed by a flicker, black screen for 2-3 seconds and video returns and I'm back in business. One extra death to show for it! So Vista is recovering ok...but it is very annoying.
Here's what i can find,
looky, at Microsoft's tech net site.
It appears that there seems to be some timing issue and Vista being impatient with the GPU or driver returning info to it. Could be fixable by M$ or nVidia. Right now it seems to be a driver issue where nVidia hasn't implemented something properly within M$'s WDDM guidelines. Anyway, hopefully this will get sorted out before too long!
Byte
Oh, btw, I'm running 156.69 drivers.