Is ir a pentium D ?
Your motherbaord would be able to work with a C2D E8200 or even a q8200/q9400, if you can find those for a cheap price used.
The graphics should be good enough for mid/low settings for diablo 3, it isn't really that taxing on graphics hardware.
Yeah, I can play starcraft 2 on medium to high settings right now, havent tried Diablo 3 but I suspect similiar performance SC2. I was looking at the 6770 and the 6850. I liked the 6850 better for obvious reasons, but if what you guys are saying is true buying the 6850 would be a waste of time as I wouldnt be getting the actual capability out of the card due to weak CPU and mobo. I wonder if I would notice an increase at all real time? My monitor only has a max resolution of 1400 x 900 60mghz refresh rate.. sad!