8800GT performs like Crap

Hey Guys, I need help!

So, I recently built a new PC and in TF2 it seems like I am getting extremely low FPS no matter what the graphic settings.

Machine is: AMD X2 5600+ (dual 2.8) GigaByte M61P-S3, 2GB Gskill DDR2-800 (5-5-5-15), OCZ 700W PS, Dual WD SATA2 7200RPM Drives in RAID 0, Running XP SP2, Direct X 9c Through GeForce 8800GT 512 to a LG 22"WS @ 1680x1050.

In TF2 I get 100+ FPS at Spawn and in intense action it can drop to ~25 FPS. This seems unusual.
I have updated all drivers including Chipset, Video (New, Old, & Beta) Tried disabling everything in msconfig, updated BIOS FW, tried various BIOS configs, unplugged peripherals and anything else I can think of. Even if I run the monitor @ 1280x1024 it does the same thing.

Any Suggestions???

How long does it stay at 25? The old 88s had a ram problem on the cards, but was elimanted with a driver update. And, does it ever go back up to 100?

TF2 is a very system intensive game because of the facial animation system. If you have graphics all the way up, try turning down textures from very high to high.

what settings have you tried, the first rule of troubleshooting is elimation, you appear to have checked most things with your system but you have not mentioned what effect changing the games settings does to the fps.

However, i myself get these same fps drops at times although not sure if it goes that low, it may possibly do that, i sue v-sync and i do notice it can drop below sixty, even though you have a better system than i, you may just be expecting too much.