That motherboard won't be good for SLI, if that's a concern. If you simply intend to buy a better graphics card if you need to, then it's fine. And yeah, at 1920x1080, the 5770 would be underpowered. The 5850 is a much better bet.
Upon further review, I'm uncertain about the power supply. Make sure to get one with Active PFC & 80+ certified. This Corsair TX 650
should be enough to power the system, or you could step up to a 750 TX.