Is this a good build?

I'd go with a stronger video card and make a couple changes, if this is primarily a gaming rig, you'd be better off dropping to a cheaper CPU to allow for higher video card budget. I'd look at something like a 7850, a 6950, GTX 480, GTX 570.. Or at least at bare minimum a 6870.

Open Box deal on a different mobo (Asus will honor the warranty):
http://www.newegg.com/Product/Product.aspx?Item=N82E16813131786R

Don't buy 16GB of RAM, get 8GB. Take it from someone whos been there, learned that.

Better deal on a hard drive:

http://www.newegg.com/Product/Product.aspx?Item=N82E16822148840