Need some GPU purchasing advice!

Current specs:

i7 930 (Bloomfield) 2.8GHz
Corsiar Dominator 6GB DDR3 1600
560TI 448 cores
1080p monitor (thinking of upgrading to 1440p)

I'm looking to upgrade to one of a 670, 680, or 7970 GHz edition.

Is the rest of my system still current enough to where a new GPU won't be bottle-necked by another component?

Any recommendations between the three GPUs with a possible monitor upgrade in the near future in mind if in fact the rest of my system is OK?

Thanks!