Someone help me with Windows 7

[mcperson2k]

Alright, well I used Windows 7 a few months ago, but my FPS in games dramatically dropped, so I quickly switched back to XP. Today I reinstalled 7 and have been trying to figure out whats going on all day... I have found lots of complaints about W7 fps issues, and just as many responses saying W7 increased fps...

My computer is old, but its not god awful...

Time of this report: 2/16/2010, 23:32:02
Machine name: RACECAR
Operating System: Windows 7 Ultimate 64-bit (6.1, Build 7600) (7600.win7_rtm.090713-1255)
Language: English (Regional Setting: English)
System Manufacturer: NVIDIA
System Model: AWRDACPI
BIOS: Phoenix - AwardBIOS v6.00PG
Processor: AMD Athlon(tm) 64 Processor 3200+, ~2.0GHz
Memory: 2048MB RAM
Available OS Memory: 2048MB RAM
Page File: 1051MB used, 3043MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 11
DX Setup Parameters: Not found
User DPI Setting: Using System DPI
System DPI Setting: 96 DPI (100 percent)
DWM DPI Scaling: Disabled
DxDiag Version: 6.01.7600.16385 32bit Unicode

What is causing this? When I say my FPS is dropping dramatically, I mean dramatically... In counter strike, I will go from a constant 100fps in 5 smokes, to 70FPS just from the muzzle flash of the gun. I have updated the display driver, I have set windows display to performance, my nvidia profile is all set to performance... Could it be that my graphics card just isnt W7 compatible?