GTX 480 vs GTX 560 TI 448 vs Geforce HD 7850 vs HD 6950?

the 480 is the stronger card, when overclocking though, the heat and power consumption curve will increase faster than the 7850's curve.

But can a 7850 perform well without any additional fans?

Even with a little OCing?

Ok. So which one should i go with?

Do you ever plan to SLI or Crossfire the card you pick? The PSU and motherboard you choose will affect this. The mistake I made when buying parts was going for a rosewill 630 watt because it was cheaper than other options. While the psu got good reviews, it certainly isn't enough for 480s in SLI. Even xfire 7850s will be pushing it, for sure, but I'd rather be looking for a second HD 7850 in a couple of years than hunting for a second 480. This was the deciding factor for me.
EDIT: so i just looked at your other posts. Crossfire and SLI seems to be out of the equation on a 500w psu, even if it is an Antec. I'm sure that Recon will do his best to give you what you need to make an informed decision.

I don't want to cross fire or SLI them in the future, since they are fairly in the higher end already and i am not going for 60+ fps in games. Oh, I was going to buy a cheap 750 watt instead of the 500w one listed.

I didn't mean to make you question which psu they picked out for you. I don't remember which one they picked, but I'm sure that it's very reliable and highly rated. I've heard time and time again that it's about quality, not just max watts. Like you, I too didn't see a need to get max settings on multiple monitors. I just like the option of knowing that I can upgrade my rig in 2-3 years with another card when I can't keep up with the new games anymore.

Knowing that the 480 is 2 years old, I can rest assured knowing this rig will last a while.