I’m going to upgrade the newer dual cores processor called AMD Opteron 185 2.6GHZ for my gaming computer.

My currently gaming computer’s specification
Operating Software: Windows XP Professional (Installed with SP2)
Motherboard: Asus A8N-SLI Deluxe
Processor : AMD Athlon 64 3200 2.0Ghz (Overclocked 2.2Ghz)
Memory: 1 GB Consair Twinx XMS 3200C2 DDR3
Graphic Card: 2X EVGA Nvidia Geforce 6800 GS 256MB GDDR3 PCI-Express on SLI (When SLI enabled, 512MB of video memory)
Hard Drive: 2X Maxtor DiamondMax 7200RPM 8MB Cache SATA (one for Windows XP Professional Software and other one is for paging file)

When I upgrade AMD Opteron 185 instead the old one (AMD Athlon 64 3200) Do you think my computer can play faster on high-end games like S.T.A.L.K.E.R , FSX, Gothic 3, Oblivion, or other high-end games on very high-quality setting?
My graphic card can overclock from 425Mhz to between 500-550Mhz and Memory 1Ghz to 1.8Ghz. When SLI enabled, Two Nvidia Geforce 6800 GS can act like substitute Geforce 7800 series.

thats weak. nvidia 6000 series cards are old. upgrade to 2 nvidia 8000 series caards, also upgrade to 2gb of memory here is my gaming rig

intel c2d 2.4ghz
2gb of memory
2×250gb hd mirrored
vista ultimate 32 bit
1x nvidia 8800 gtx