HDD: This is a much faster drive. It uses 500 GB platters, so the data density is higher and can be written/read faster.
Case: This is the best gaming case out there. Or at least one of the best.
GPU: nVidia is dead until Fermi comes out. Avoid them like the plague. You also want a much more powerful card than that for any gaming.
PSU: Higher quality for a little less.
RAM: These sticks are much, much faster. They're also better for overclocking. You also don't need 8 GB of RAM unless you're a heavy, heavy encoder.
Mobo: This one has USB 3/SATA III and Crossfire.
HSF: This is easily one of the best coolers out there. It's also one of the cheaper ones.
Instead of the 212 I think that the sunbeam CR-CCTF will be better, as its a little better performer than the 212+ and its also cheaper http://www.newegg.com/Product/Product.aspx?Item=N82E168...
is 40 bucks minus $15.00 in MIR thats $25, and the 212 comes out to $42.55 after the $7.56 charge of shipping is included.
thats it, the rest seem like a great build, good work MadAdmiral