I was thinking about that after I posted. From the reviews I saw it's give and take between the 7750 and the X2 6000+. Given they have the same architecture, the 3GHz 6000+ *should* be about 15% faster than the 2.6GHz 5050e. So from that, I reckon that if you're looking at CPU alone it probably would be worth it. On the other hand, if you're playing games at a resolution where your CPU is limiting your frame-rates, you're probably getting more than 100fps anyway, so does it matter?
Good call though, from a CPU POV: again, I'll have to seriously consider it for my next build (assuming I don't go Phenom II X3, or that the new Phenom II based Athlons aren't available by then!)