Big, he also said he could get one for $99. Compare the performance of the GTX260 to the 5770, and the GTX260 is faster. It just uses more power and doesn't support DX11 which currently isn't a huge deal.
Rumpel, I wouldn't worry about it to much. I've gone from a TNT2 to a 9600AIW, 9700pro, x1800xt, 8800GS, to my current 5750. Honestly? Other then the performance I can't tell any difference.