Just for the heck of it, have you tried moving the folder for your Temporary Internet files?
Create a temp folder off the root of c: and move it there.
According to MS:
http://www.microsoft.com/whdc/device/display/graphicsmemory.mspx
"Shared system memory is a portion of the system memory that can be used by the graphics subsystem when needed. For discrete graphics adapters, this type of memory is often referred to as non-local video...
Actually there is an easy way to do this (In Vista Business anyway).
Just run secpol.msc then local polices > security options > user account control
and change the behaviour of the elevation prompt to "elevate without prompting"
I'm not sure if this works in the Home versions or not.
I would start by forcing Vista to display the BSOD instead of restarting.
Rt-Click Computer>Properties>Advanced System Settings>Startup and Recovery settings>Uncheck "automatically restart" under System Failure
What it sounds like to me is that AT is saying that Superfetch will make it more difficult to get benchmarks to be consistent, just running in Vista alone. Forget about the comparisons to XP.
You may get varying results depending on what's in the cache. A game may run faster after running...