T2A if you've had the machine 2 yrs and done no maintenance, then I'd reccomend running as many virus and spyware sweeps as you can, uninstalling programs you no longer use, making sure you don't have many 'backround' prgrams running when you play, and even consider cleaning your registry and doing a defrag after everything else is said and done.
I do agree that it sounds like your CPU rather than the vid card is the one taking a beating for some reason. My first bet would be the backround programs eating up some extra cycles but there shouldn't be enough to cause the game to chug that significantly.
Still, if you haven't done any maintenance, then I'd suggest going through the above list.
Could also consider some BIOS flashing and even check the windows update but we all know those are 'dangerous' tasks, lol.
Good games Fri night. Thanks for the fun as always.