I remember seeing in some video that some guy got 41.9 FPS with a 690 at 1080p.. Scary stuff, although since the 7970 is roughly equal to a 590, its safe to assume an 8970 is roughly a 690 and so the next generation of cards will be fine. At your low resolution, it might be fine, but definitely not at high settings. Use Crysis 2 with MaldoHD 4.0 to get a rough answer.
The alpha did not support SLI/CF, which is why the 690 got that performance. A 7970/680 was pulling around 40fps average in the alpha at 1080p.
So I doubt that a 7770, which is less than half as powerful as a 7970, will be able to max it out at 1440x900. It will definitely be playable but you'll be turning some things down.