the reality is I play most of the big games out, and to be honest don't notice any major issues, the odd stutter here and there but that's about it. However with the newer titles I know to leave AA alone etc and wonder if the 460 would allow me to start 'fiddling' again
I have a similar system Q9650 at 3.8 and 4 gigs, same mobo too and a GTX470
I upgraded only last weekend, from a dual core also at 3.8 and a OC GTX280, i game at 1680 by 1050
I also have XP so DX9 basically, but now i have a 470 i might get win 7, not sure since the number of DX11 games seems quite low at present
The long and shorts is i did notice a small improvement on BFBC2, it was smooth before on high settings but the frame rate did fluctuate while you were running around, post upgrade, it seems rock steady i'm guessing it's a pretty constant 60FPS no noticable fluctations at all, i not really played any other games since i only had it couple of days, but i'm guessing new stuff might see a small increase, old stuff none at all
It could also be the Quad upgrade, i hear BFBC2 likes a quad
End of the day, this upgrade will see most benefit with a few very demanding current games stuff like Crysis (i might finally pick it up now i can run it in all it's glory), BFBC2 will benefit, even more so if you run in DX11
It will also benefit future games, Dragon Ages 2, That bioware starwars RPG, BFBC2 Vietnam (which looks a fab expansion), you get my drift
Personally i would get a 470 over a 460, it's not that much more, and with your quad at 3.4 should see you set for top quality gaming for another 18 months, if you upgrade do so on the basis of being able to run all current and the next 18 months worth of big demanding titles, the upgrade will show it's worth over time, current games like BFBC2 from what i can see seem run with a more stable framerate, but i bought on the basis of getting good quality gaming for the next 18 months rather than to massively improve any current games