Thanks for all your help. I downloaded some new drivers over lunch and installed them, so tonight when I get home I'll see if it's running any better. I have another game I can try as well. Maybe it's just a halo (1), vista conflict or something. Thanks for all of your help today..
If I'm not satisfied, it looks like I will be getting
~geforce 8600 gt (possibly gts) video card,
and ~400 watt psu.
I talked with the it guy here for a few and he said if I'm nervous about the psu at all just bring it in and he'll help me out. I hate pulling/pushing all the connectors onto circuit boards. I've had awful experiences breaking them, bending them, etc..
Thanks again for your help!! I learned a lot today!!