well, at least the 560 Ti can do high def gaming till next year, and certainly can play games less than high next 3 years,
but not the GTX 550 Ti. It cannot do high def gaming today, it can only play medium settings. I have experience with this 550 Ti dude. In witcher 2, GTX 550 Ti averaged 25 fps paired with my 4.2 ghz i5 2500K.
Now is a different story, i am currently using GTX 670 after a roller coaster experiences with different Graphics card.