I have a Geforce 8800gtx and not just multi core but quadcore qx6700 on vista.

I think these days you will find that people that actually play games will have a late gen pixel shader 2 card or a pixel shader 3 one. And most CPU's for the past year and a half have had some form of hyper threading or multi core ability.

For example if you visit the steam hardware survey you will find:
http://www.steampowered.com/status/survey.html

Physical CPUs
1 cpu 930,100 86.49 %
2 cpus 144,516 13.44 %
4 cpus 757 0.07 %

Cards which default to DirectX 9 Shader Model 3 Path on Source (446670 of 1075366 Total Users (41.54% of Total) )
Cards which default to DirectX 9 Shader Model 2 Path on Source (273352 of 1075366 Total Users (25.42% of Total) )

Hi PHeMoX

Yes but instancing can be done using shader 2 or 3, 3 is better I believe hardware instancing.