Do your games load textures off the CD/DVD while playing? If you have the space see if the installer will copy all textures to the hard drive. A swap file might help as well. It would allow the game to preload textures to the faster hard drive before it needs them.
My machine is an
HP a6130n:
AMD Athlon X2 5000+ with 3 GB RAM,
8600 GT vidcard / 256 MB DDR3 (I allow it to take up to 768 MB of System Memory as needed),
Hitachi 400 GB 7200 RPM ATA133 w/ 8mb cache.
I use onboard sound though for two reasons. 1) I wanted to keep the computer less than $900 retail and 2) I am tone def so can't tell the difference between most onboard and expensive sound cards anyway.
The video card is the only addon that I have with it. Cost me $130.00 at Newegg. I went with a prebuilt PC because I needed it that night due to my last PC dying and it was actually cheaper than building it myself once the cost of Windows was added on.
I attached my dxdiag.txt file.