It can play games, but you won't be able to play all games at max graphic settings.
See following for benchmarks. The 1440x900 resolution has almost the same number of pixels as 1280x1024 resolution so the benchmarks should be similar. Note that the CPU used in the test rig is an Intel Core i7 920 @ 3.8 GHz.http://www.techpowerup.com/reviews/AMD/HD_6790/5.html
If you use Metro 2033 as an example, then the HD 5770 is already inadequate to max out the game.