What resolution are you playing at? If you are playing at 1900x1080, than you'll be playing on low settings but it will play it around 30fps or so. If you are playing at 1280x1024, you should be able to turn the settings up some to increase your gaming experience.
Even the highend graphics cards like GTX 295 and ATI 4870x2 have problems with some settings on Cyrsis. If you are looking at COD4 or games like that, you'll be able to enjoy your gaming with the ATI 4770. You might not able to have all of the "eye-candy" on but at enjoyable settings.
The lower you go on your resolution, the higher you can set your settings. You might be able to get to ultra high settings at 800x600 but I can't say for sure... you don't find many benchmarks for that resolution. Also. overclocking your CPU will help with your settings, so I would look at that route too.
ur spec should be ok... N260GTX managed to play crysis on high setting or possible ultra high with lower resolution and other game like COD4 sure fly into to sky lol...N260GTX just like HD4770 or 4850 if i not wrong...