The HD 5970 outperforms the GTX 480 in almost every instance - which is to be expected. There are several threads in which people have been debating this issue, but at the end of the day, the HD 5970 is still a multi-GPU card. It would be unrealistic to expect the GTX 480 to keep up with it.
And with regard to Crysis 2, it seems unlikely that Crysis 2 will be the same sort of GPU-destroyer that its predecessor was. Unless the game has massive potential on the PC that just isn't possible on a console, Crysis 2 is probably going to be much more accessible at higher details than Crysis was/is. Until the game is a bit closer to launch though, it's a hard to say.
Personally, I would (and did) go with the HD 5970, if you have the budget for it.
5970 unless you plan on getting a 2nd 480 down the road (but at that point people would be about getting 2 5870's for cheaper which out performs a 5970) or doing alot of folding apps the performance diff is too large to ignore.
HD 5970 performs better but GTX 480 got physx. And also its nvidia. THE WAY ITS MEANT TO BE PLAYED! NN ati ewww.
Didn't you just post a thread about how you may have fried your new GPU by "just playing around with rivatuner for fun lol"? No offense, but that makes it tough to put much value in your GPU advice (especially considering the brand-name favoritism demonstrated in your "the GTX 480 is better because it's nVidia LOL" post in this thread).
There really aren't many 'folding apps', most other clients have updated to a standard that is far better than F@H which is simply crippled until they update the core. The HD5970 would outperform the GTX480 if it was given equal access to LDS.
I would say for anything you use regularly that is coded in CUDA go with the GTX480, for more OpenCL and Direct Compute stuff that's more universal, then both will perform pretty closely depending on their requirements (although single precision is actually about 4:1 on the HD5970, but it's hard to exploit as you can see from the Sandra results where Fermi and the HD5970 are neck & neck).
The 5970 would be better on performance. Many reviews say this, and if you wait until the GTX 480 is out, than probably the ATI champ will lower their prices, even if it outperforms NVidia. And as of yet, both cards are overkill unless you have a big resolution. At 1920x1080 res, ATI 5970 is overkill for Crysis. Not really sure about Crysis 2. NVidia has PhysX, but the only GOOD game that has it is Batman, so go with ATI. If you go with ATI, make sure you have a good cooling system, as it tends to overheat.