Mass Effect 1 on PC glitches

I downloaded mass effect on PC from steam. It would not run through steam initially so I found the executable file and have been running it as an administrator in windows xp compatibility mode. My problem is that game runs very choppy and lags, but it does not seem to be due to hardware requirements. The temp on my graphics card barely increases, I tried lowering the settings to see what would happen and it didn't help. And it almost acts more like glitching than lag. Some of the conversations will cut off before they are done. When I walk down stairs it seems to glitch out, and certain doorways will glitch for example. Am running the game in 1680x1050 (standard for my monitor), tried changing to lower resolution, did not help.

Things I have tried: 

Disabling VSYNC.

Turning off catalyst control center

Uninstalling/reinstalling

Lowered graphics settings to lowest setting

Tried switching the affinity to change cores but it said access denied

Installing patch v1.02

I am running:

Windows 7

Visiontek Radeon HD 3870X2

8GB DDR2  RAM

Intel Q6600 Quad Core at 2.4Ghz