Okay, here's the deal: I just had another Vista program hang- was playing
"Blitzkrieg" WWII RTS by Nival Interactive. The company claims the program
is compatible with Vista, and I agree, as I haven't had the nightmarish
install problems I have had with other programs, and only had to disable
visual themes in the compatibility settings.
Anyway, the game hung yet again.
I did ctrl-alt-delete to unlock the computer (this sometimes works in Vista)
and while I had Task Manager open, I checked the Resource Monitor.

An instance of svchost.exe was getting literally thousands of hard faults
per minute. Physical memory usage was only 58%.

game.exe (the exe for Blitzkrieg) was showing 0 hard faults per minute.

Right now, with just task manager, IE 7 and the resource monitor running,
Vista is still throwing hard faults at only 68% memory used. I can see and
hear the HD running. That would explain why the new PC is such a dog, if
it's constantly in virtual memory.

Yes, AV is installed and up to date.

Am I wrong, or should Vista not be using virtual memory until I hit 100%
memory usage?

If it were a matter of hitting 100% memory usage and Vista having to dip
into virtual memory, then I would just go out and buy another MB or three of
memory and be done with it. But it looks to me like that's not the problem.

Aha! I just looked again- no hard faults right now, and I haven't done
anything different. This might explain why sometimes games run, and
sometimes they hang/crash/refuse to load. Gonna run another virus scan when
I log off just to be double sure.

Anyway, any help would be very much appreciated.