had the same issue here... upgraded from a 6850 myself. love the 7870.. its only a small hurt that it isnt the 670:)..
but you'll do good for most stuff... and frankly it can give pretty good 1980 performance.. its only the 2K plus resolutions that arent that brilliant.
Sounds good, I dont play any of the games that make GPU's cry, the most intense game I currently am playing is SWTOR and the 6850 handles it ok at high settings, just not maxed settings and I want to max. As for resoloution, I dont see myself going for any higher resoloution anytime soon, my current setup, the monitor barely fits.