Originally Posted by
Cantii
IMO you should only use micro ATX boards in an ATX case if you don't care about convenience, since most of the time the video card will heavily overshadow things like SATA ports and the like, but that's up to you. You also might want to consider spending the extra $30 and get the Crosair HX series 650HX, for the sole purpose that it's modular and will save you A LOT of time and headache in cable management.
As far as after-market CPU heatsinks, unless you intend on overclocking, the stock will be fine. I do, however, recommend taking off the existing thermal compound from the stock heatsink and using something else, something like Arctic Cooling MX-2 or OCZ Freeze. Stay away from Arctic Silver, there's a lot of hype behind it and it requires some pretty ridiculous feats to get it to set properly. Arctic Cooling MX series and the OCZ Freeze series severely out-perform Arctic Silver anyway.
Asus is good, but they're not the be-all-end all of PC parts. The HIS HD6870 is a rockin card, so is the XFX HD6870 (I actually recommend the XFX HD6870 over all else just for the double lifetime warranty). There are also far superior cases to the Asus Vento (CM Storm series cases for example, as well as CM HAF series, Antec 902 and 1200 are superior as well, 300 as well). I love Asus myself, their motherboards are some of the best, but there's no special super awesome setup when you go with all one company -- it's not a set bonus.
As far as memory goes, LGA 1155 actually has the sweet spot with 1333 MHz RAM, and you won't notice any difference going from 1333MHz to 1600MHz on an LGA 1155 board. LGA 1156 and 1366, however, have the 1600MHz sweet spot (1366's sweet spot is really anywhere between 1600MHz and 2200MHz due to the enthusiast nature of the platform). GeIL makes good RAM for the price, as does G.Skill, might also want to check them out (aside from Corsair, G.Skill is one of the top selling RAM kits in the U.S., solid product).
Also, when concerning latency, RAM is a tricky. Lower latencies shine at lower clock speeds, and vice versa. That CAS 7 1333MHz DDR3 will perform pretty much the same as that CAS 9 1600MHz DDR3. Now if you're going extreme with CAS 6, then higher latency RAM needs to be ~1866MHz or higher to compensate. However, lower CAS memory is not in the budget, so that's not even moot.
P.S. - Samsung SpinPoint F3s are better than WD CavBlacks, just FYI.