The HD 7970 and HD 7970 GHZ Edition are the same cards.
The only difference is that the HD 7970 is clocked lower.
They both however reach the same frequencies through overclocking, so there is basicly no significant difference between them.
They also cost the same.
Just buy the card lethalsam suggested.
It's the best offer i've seen so far.
get a 7970 and overclock it, AMD is still constantly improving their drivers, I think 13.1 fixed major latency issues with Skyrim and a few other games. I have not seen to much about Nvidea drivers lately though.
Nvidia just has much better latency in all games, except the 3+ games AMD has fixed.
Yea, i haven't really looked into latency tests to much, but I will when the 700 series comes, mainly because ive heard they have better drivers than AMD, and personally I don't mind paying a little extra for a nice card.