Well pre Quad Core and 470 upgrade, i had the exact same rig but with a Dual Core and GTX280
My Dual and Quad were both clocked at 3.8 and my GTX's were both OC to 700 core
Pre Upgrade on BC2 i got FPS varying from 60 to around 20 in very heavy action scenes, depending what was happening, now this may have been the Card or CPU holding things back (I hear BC2 likes Quads) or maybe a bit of both
All the prev games i was playing before i picked up BC2 ran at pretty much 60FPS or there abouts right the way through for the most part and my perception of the smoothness of BC2 was affected by this, the game was pefectly playable but the fact the FPS were never stable constantly shifting around meant that although generally smooth it did not have the fluidity i had got used to, post upgrade it now runs a pretty constant 60FPS, which is how i like it
As to if you notice the differance between a rock steady 60FPS or a FPS fluctationg between 60 - 30 FPS depends, i guess some will notice more than others, for me personally V sync + a stable 60FPS is what i look for a new card to deliver on games for at least 18 - 24 months at my 1680 x 1050 res, which my old 280 managed, and i'm hoping my new fairly recent 470 will do the same honours, at the time of my 470 purchase only the 480 was available and it was quite a bit more for not a lot more performance, kinda like the differance between a 260/280 but a 280 was not over a £100 more than a 260, so i got the 470.
This new card looks good but will probably be expensive, it could make 480's a good buy though depending on how much they drop in price