My 4870x2 died yesterday and i had to choose between the GTX 480 or the 6950 (6970).
I looked at the benchmarks for both and compared and found that it was pretty much 50/50 on which one was best.
So i decided to go for the 480, purely because the 4870x2 was my first ATI card and the drivers where a pain and it's died on me in 2 years, yet my 6800GTS is still going strong.
Nvidia wins!
Sorry to hear about the 4870 X2

Even though I slightly favour the 6950 (unlocked) over the GTX 480 due to heat, power draw and being new over the EOL GTX 480. I'd still be happy with one if I had it in my rig. I wouldn't swap my card for one now but for £20 cheaper than I paid for my 6950 when the GTX 480 deal was on, I'd have bought it easily as I would get my true resolution out of my CRT gaming monitor as well as be performing similarly to what I am now.
Enjoy your card as it's a really great performer. I've been gaming on my friends i7 @ 4Ghz with a single GTX480 and now SLI as he bought another one. I think it's a brilliant card. Heat doesn't bother me that much but power draw does slightly and being EOL. Apart from that, both cards overclock well and perform closely.
What I'm really interested in seeing is a 900Mhz core GTX 480 vs a 950Mhz core unlocked 6950. That would paint the picture I'd like to see.