I pulled the 512 and it's working fine. Thanks a lot, I'll keep in mind to try to get the exact type of RAM that's inside currently, and I'll let you all know how it goes.
I know about dxlevel 70, and the rate commands. I was thinking it was my ram :)
I'd rather not get another graphics card, so should I pull the 512 stick until I can get another gigabyte?
Nvidia GeForce 8400 GS (lowest settings)
Intel Pentium D Processor 820 2.8ghz
200gb (plenty)
1gb stick DDR2 ram, one 512mb DDR
My average FPS in team fortress 2 is 20-40, CSS it's 50+.