i have been working on building my pc for a while and dont know what games it can play at 1080p
amd phenom 2 x2 oc 4.0ghz
corsair vengeance 4gb 1600mhz 9 cas upgrade 8gb later
asus m4a78td-v evo/usb3
amd 6870 coming in mail in a few days
windows xp 32bit upgrade windows 7 64bit later
way to much cooling i was cautious lol
had to get fan controller 2 quiet it when watching netflix
640gb sata 6.0gbps western digital upgrade 4 750gb in raid 10
corsair 650w power supply
lots of mods dust filters and junk on antec 300 its kewl
name games i can play between 720p and 1080p and ok fps
Looking at your specs and going off modern games (for reference i'll be using Bad Company 2, Black Ops etc) I would stick to 720p to maintain good frame rates.
The dual core Phenom is limiting your potential here, is there any possibility to upgrade to a quad core? The 6870 will handle 720 fine, but may struggle at 1080. If you want to go to 1080, then I suggest turning settings down, AA and other post processing effects off.
Actually, if your CPU is the bottleneck, increasing the resolution shouldn't change much as it's mostly GPU strain you will be adding. You will probably be able to play many games decently with that card; up until about a month ago I was still running an Intel E8400@3.6Ghz with a GTX 260 and I could play most games at 1680x1050.