Sollid gaming rig! You wont see any real world performance difference betwee nhte i7 920 and 930... so i'd say save a little bit and go 920. Also, the new GTX 460 1gb is barely below that 5870, but half hte price. You should buy it...if you can afford it buy two in SLI!
GTX 460 is WAY below the 5870.
The GTX falls between a 5830 and a 5850...you could call it a 5840 if you like. It does overclock very well, falling just beyond the 5850.
However, the 5850 can Overclock to near 5870 performance and is a better card. So far, the 5870 is still more powerful than the other two cards overclocked, and that is before you consider Overclocking the 5870.
So, don't settle for a GTX 460. I think the fact that Nvidia finally made a well designed card has got people a bit overexcited regarding its ability. While it is a nice card, it was still designed simply to beat the 5830 which is itself not a great card.
I have to admit, me personally, I would drop to an i5 750, an Asus P7P55D E Pro board and 4gb of G Skill Eco 1600mhz RAM CL7. The i7 offers no real performance improvement for gaming and costs a lot more money.
This is with an i5 750 w/o win 7. I skimmed over your post and didn't see "i have" to the OS. When it comes down to the case I always say go with whatever you'll like to look at every day, and that functions the way you want. There are four other cases that you could use in the place of the one I used including the HAF 922. Also look at what has free shipping or cheap shipping, because cases can become overpriced really quick.