IIRC, GTA4 is both a GPU and a CPU hog. The IVY chip, even if it's an i3, should be good enough to take care of the CPU portion smoothly enough. The 6670 is not ideal, but as Jim noted there, 1366x768 is a ton less load than most benches are done at, I'd have to guess it would be no slower than an Xbox would run it worst-case scenario. On that note, if you have an HDTV in addition to your monitor, it might work well with HDMI out from the 6670 at 1280x720 on the big screen, even if it's a 1080p HDTV, at that distance with those settings should look good. It's not always easy getting PC to play nice with HDTVs, but something to think about. For the monitor, you definitely want to stick with native 1366x768 or it will look horrible.