Everything looks pretty good, I personally would make 2 changes.
-Grab 2 Samsung Spinpoint F3's as HDD's, same price and double the capacity. Also, they are faster than the WD's so there's another plus.
-Do you REALLY need that sound card? Nowadays, onboard sound is very good. Unless you have a very good speaker system or $200 headphones, you most likely won't hear any difference.
Other than that, nice build! Gonna be a super system.