nvidia cards should not be even be an option for your build. they have a terrible combination of price/performance, while ati has three excellent performers at three different price points. the ati cards are quieter, cooler, and use much less power.
also the i7-860 is a bad choice. the i5 has better performance for gaming and is cheaper, and if you need hyperthreading the 930 is a small bump in price and much faster.
in the end, the i5 with a 5870 or a 5970 will be great for games at your resolution. if you decide to go with the 5870 you may be able to fit in an i7-930 into your budget.
good luck with your build!