The 560 I linked was $125 after rebate (and the other was $130), so if you are willing to wait for your money to come back, it's only $15 more. And we aren't talking a small difference here. Pay 10% more and get 40% more performance? Sounds like an obvious choice. Of course, you may just not have the money, but the 560 is far and away superior to the 550 Ti. Look at that benchmark I linked above again.