RAM seems fine, but I'd recommend the Gigabyte motherboard (there's also a combo deal with the CPU you'd like to buy, save yourself 15 bucks). Sadly, it does not support DDR3 1600 specifically, so you'll have to poke around for different RAM, try the "G.SKILL 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333."
Otherwise you're pretty well off, double check what wattage you'd need to run two 5850s in CrossfireX, assuming you'd like to do so in the future.
EDIT: I've had the case personally, and it's alright, but I'm unsure if it'll fit the 5850. I could measure for you if you'd really like to know.
ah i didnt notice that the gigabyte mobo didnt support that ram... but does the gigabyte mobo do crossfire at 8x or whatever? and apparently if you do use crossfire with that board then the usb 3.0 and the sata 3 dont work... so it didnt seem that important
Also, is the low voltage ram really that important?
And can anyone recommend another case that would be nicer/bigger if it needs to be?