The build looks good for your intended use. How firm is your $850 budget? If it's slightly flexible then I would consider upping the RAM to 8GB. CAD software likes as much RAM as you can throw at it as long as you have the 64-bit version of the programs. You could go with a slightly cheaper case like the Antec 300 to save a few bucks toward the RAM. You could also save some money on the PSU since 750W is major overkill for this system.
I agree that the 750 would be overkill, but i heard that corsair makes good PSUs and that model is on sale for $90, that is $50 off. i did a power check and the min. needed is 550watts so i thought i should just add on 100 w to be safe. then i saw this PSU on sale.. then i thought.. better be overkill then underkill. I'de say I don't think i would need to go over the $850 unless something would make it 10 times better for an extra $100.. but i could get 2 of my ram packages for total of 8 Gigs..
Hey cgroom, I'm looking at building an i7-860 build also... my thread is called "<$1000 gaming/video editing desktop!". I noticed we have picked out some similar components... GB motherboard and g.skill ram.