Good case choice - I have a Silverstone HTPC case and it's excellent. However there's no point in purchasing a GTX 570 - get a Radeon 7950 or a GTX 660TI instead, those are far better GPUs. Also no point in 16GB RAM for gaming. Also power supply is important - make sure you get a good one from Corsair or Seasonic.
It should be an excellent gamer! I agree with the last comment that if you don't already have the GTX570, then you'd want to get one of the newer cards at the same price point that are a little less power hungry and run cooler. If you already have the 570, then it's still a very relevant card and game on!
-cut the ram to 8gb. there is some patriot ram on sale at newegg
-cut on the board. overkill.
-get a less power hungry card. a 660ti or a 7870 will do
-make sure you get yourself a samsung 830
-i use seagates but WD is good as well