First I'm going to explain my Detailed Specs.

CPU:
Intel Core Quad q6600 @ 2.40Ghz


This is My GFX:
2x Nvidia GeForce 8600GT

Default Memory Clock 400Mhz (800 With SLi)
Default Core Clock 540mhz (1080 With SLi)
Memory Capacity : 512MB


RAM:
2x Kingston DIMM DDR2 660Mhz


Hard Drive Capacity 500GB


OS:
Windows Vista Home Premium

Power Supply
450 W

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About the Settings i have:

Everything high @ 1152x864 No AA

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the Problem is that it's running on 15-20 FPS And i was expecting much faster...

So you guys can help me out by finding what Spec is low on peformance.
i hope it's not the Graphics card...

Oh, btw, I have overclocking gexperience.. Should i try it?