Well, if it has worked for a few days after installing there's obviously something screwing it up when you've installed/updated components after that, which is now hogging up some data/temporary files pretty badly. Try to think of a list of EVERYTHING that might be running in the background, and shut it down. Also try to switch off windows Aero as much as possible, it's pointless and will only stress your CPU/GPU more for shiny looks.
Other then that the cage on your CPU is plain.. Horrible, as is the bus and pretty much everything, now I know it never uses 100%, but that MIGHT be because it dumps that data and processing prematurely because otherwise it'll either overheat or simply crash itself.(Using an AMD Phenom II ~3.2ghz X4, my cores never reach over 30% CPU usage, but sometimes I still get some lagspikes when using my older GPU to test my rendering engine on
)
Another issue might be the speed of your RAM, most DDR RAM is ~400mhz, while this is sufficient for most every day tasks for actual games with a large amount of data to store and handle along with your OS that might not be fast enough, I mean quantity is meaningless on most systems because people tend to either overlook the 32bit limitations or simply ignore the speed of the RAM because they're cheaper.(Note that DDR2 RAM usually starts ~600-700Mhz, I myself use 8gb of ~1333Mhz DDR3 RAM, which does the trick quite well)
Anyways, as a last thing I can say is open your Nvidia control panel, and in the 3D Settings turn EVERYTHING to performance mode, or switch it to application control mode.. Whichever you feel more comfortable with, as well as switching your resolution to ~1024*768 in-game, these things tend to influence your FPS a lot more then you'd think at times.(Using an ATI card myself, haven't used Nvidia since the 6 series
So can't be of much help on the settings window.)
Your issue is most likely not a simple one to pinpoint, mostly because the information you hand out is fairly vague, and your responses to people their help seem somewhat short tempered and unwilling to try at times. And out of curiousity, do you have ANY drivers installed for your motherboard AT ALL? This sometimes causes issues as well.
