The 7750 will serve you well,had a gtx650 which is nearly identical performance wise and i found in my older games like BF2 and UT3 where i used to get a certain framerate with my old 8800gts 512mb that i got a way better overall experience with the gtx650.
With DX11 games the gap should be even further,got your 7750 consuming nearly half the power of a 8800gt while being faster and years cooler with half the noise,its a win all around for a budget card trust me.
Hey thanks yes I'm already convinced about the 7750 being 50% better or more than the 8800gt, we were just talking about whether the 7770 might be better.