Will the system in my sig be able to render doom3 smoothly while still looking awesome or do you think I will have to sacrifice significant image quality?
Medium quality (some texture maps are compressed) at 800x600x32 will probably be alright. Might have to go 640x480 to keep it fairly smooth in big firefights.
depends on your standards for good graphics. I suppose if you never see it in it's glory then you will be ok, it's when I take peeks at high res screenshots with high quality settings that makes me want to get something faster/better.
you should be ok, just don't go looking at screenshots.