275 GTX Problem

[brains1cK]

So, I've tried searching all over the internet to find some sort of solution to my problem, but nothing seems to work. My problem is that when playing CoD4 and MW2 I get EXTREMELY low FPS and a high ping, however I'm on campus and get very good internet. The game responds quite slowly and choppy. However, on games such as CS:Source I get a good ping with FPS anywhere from 90-160. I've tried reinstalling the graphics card drivers, checking the power connectors, all of that stuff, but nothing is working! Also, I ran 3DMark Vantage (the new one that uses dx10 or something?) and my CPU score was 14000 and my GPU score was about 3500; I'm assuming that's very low for a 275 GTX. My overall score was about 4200 or so.

On a side note, I just defragged my hard drive and cleaned my registry using CCleaner. Also, if applicable, I only have about 57 processes running...none of them are taking up an unreasonable amount of CPU usage or anything from what I saw.

My computer specs:

-Core i7 920 2.66GHz
-Some $60 Zalman Heatsink and Fan
-Windows Vista 64-bit
-eVGA Nvidia 275 GTX 786MB (Or whatever the amount of memory is..)
-6GB Corsair Dominator DDR3 Triple Channel
-2x 640GB Western Digital HDDs (One of them doesn't show up, which is another problem I'm trying solve)
-850Watt Corsair PSU
-eVGA x58 Motherboard

Help would be GREATLY appreciated!!! This problem is driving me crazy.

-Thanks

 

[brains1cK]

*BUMP*

Someone please help!

By the way, I just ran 3MMark 06 and got a score of 2670...that can't be good.

Also, I'm using a 23" Monitor