Dunno if this would help for MAME, but for standard gaming, it might.
Check it out for yourself - my XP box is being set up for my jukebox, and it didn't make a difference for that application that was noticable.
Game XP (http://theorica.click-now.net/gamexp.htm)
There has been a report of browser hijack software bundled in with this. I can neither confirm nor deny this. Since it didn't make a difference on mysetup, I deleted it. Will download again to see for myself.
If you're so inclined, give it a whirl, see what you think.