CS:S hardware/software issues?

I've just purchased Counter-Strike Source, and for some reason it's running choppy on my system.

I'm running it on an nVidia 6800 GTOC AGP 256MB card on a Pentium 4 2.4GHz PC with 1GB RAM, but I'm getting some horrible video. Vertical Sync is disabled as well. Usually on CS 1.6 I have 100+ fps & 20-30 ping, and runs great on an OpenGL 1280x1024 resolution.

I've lowered all of the Advanced Video settings in CS:S to 'LOW' and the resolution to 800x600, yet everything still runs choppy (even while playing BOTs on single player mode).

I don't have any extra applications/ad-ware running in the background (just reformatted this PC). Would creating Virtual Memory resolve any problems?

Any help is greatly appreciated.

Try running it in direct x 8 or 8.1, direct x 9 might be the the issue. Also make sure you have the latest version of direct x from microsoft and expecially that you have the latest drivers from nvidia.com

Thanks.

I have the latest drivers + software, though, I'm not so sure how to configure CS:S to run on DirectX 8.*.

First enable the console by going to Options -> Keyboard -> Advanced. Then Press ~ to bring it up, in there type mat_dxlevel 80 for direct x 8.0 or mat_dxlevel 81 for direct x 8.1.

Otherthings you can try for a performance boost are:
r_dynamic 0
mat_bumpmap 0
mat_specular 0

You could even drop your direct x to 7.0 if you want to but its not normally worth the performance gain.