It isn't the most demanding game out there by far, but the HD3300 IGP on a 790GX can play Guild Wars on 1440x900 at over 45FPS with some eye candy. I haven't tried it on a 780G with the HD3200.
Hopefully, however, a discrete video card is a valid option for this system. If you're concerned about power requirements, get a HD4670 (or HD4650), which does not need auxilliary power.