The 7970 is pretty much the top card right now, prices on the new ones will be high, they may not be out for months, and a 7970 will last a few years anyway. It ALSO comes with crysis 3 and Bioshock infinity free if those interest you. Should both be great. I wouldn't worry to much about waiting if you want it now. Really its up to you.
Side note, an i7 is a waste of money for gaming, an i5 makes way more sense and performs the same. You might also want to get some memory