huge performance decrease, graphics card. PLEASE HELP

Ok, so, a few months ago, i got this brand new computer:
iBUYPOWER GX-525 Phenom X4 9850(2.5GHz) 4GB DDR2 500GB NVIDIA GeForce 9800 GTX Windows Vista Home Premium 64-bit - Retail

from newegg.com:
http://www.newegg.com/Product/Product.aspx?Item=N82E16883227068

the specs are:
AMD Phenom X4 9850(2.5GHz)
Processor Main Features :64 bit Quad-Core Processor
Cache Per Processor :4 x 512KB L2 Cache
Memory :4GB DDR2 800
Hard Drive :500GB SATA
Optical Drive 1 :20X DL DVD+/-RW Drive
Optical Drive 2 :16X DVD-ROM Drive
Graphics :NVIDIA GeForce 9800GTX 512MB Video Card
Audio :ALC888 8-channel CODEC
Ethernet :Built-in GB Ethernet LAN
Power Supply :800W
Operating System :Windows Vista Home Premium 64-bit


and when i first got the computer, everything ran wonderfully. I could play company of heroes on high detail at 60fps, and my Windows Experience index was 5.9. Now, for whatever reason, my Windows Experience Index is 2.0:

(you have to click on the picture to see it)
As you can see from the picture, my Processor and RAM and Primary Hard disk are running fine, but my Graphics and Gaming graphics are down to 2.0 and 2.5.

I first noticed this problem a few days ago, and i downloaded numerous spyware and anti-virus products, which didn't fix it. I then formatted my hard disk and reinstalled windows with a clean installation, and it is still a problem. I have updated my drivers for my Nvidia 9800 GTX and it hasn't helped either.

I really don't know what to do now because not only can I not play any of my games (they run like slideshows, 1 FPS), but my system is also a little slower than usual. PLEASE HELP me MAJORGEEKS!!!!

 

oh, and another thing. im not sure if this is part of the problem, but a few days ago, BEFORE I REINSTALLED WINDOWS, one of my friends was playing runescape on the computer...

 

Give GPUZ a try.

http://www.majorgeeks.com/download5796.html

It's a program designed exclusively designed to detect and provide info on your VGA card.

Also, have you tried playing games with the graphics settings on low? Try turning every graphics option down as low as possible to see if you get any improvement.

 

Alright
i tried GPUZ, and i think that the problem is that my card is for some reason running slower than it should be. here is a screenshot of my results: View attachment 97539

the odd thing is that on the NVIDIA website http://www.nvidia.com/object/geforce_9800gtx.html?startgom=1, the specs show up different than what my card is running

-my GPU clock and memory clock are running at 400 mhz, and the nvidia site says that the graphics clock is 675 mhz and the processor clock is 1688 mhz

what should i do?