Here's a couple of things to think about.
Instead of a Raptor, go with two Seagate Barracuda 7200.10 250GB 16MB cache drives in a RAID0. You get almost the same speed with almost seven times the storage for the same money. Then (if you can afford it) get a 500GB drive to be used as a mirror of the RAID array.
On the motherboard, I read that the 965 chipset won't be compatible with quad cores (looking down the road here). if you're not worried about that (don't plan on upgrading for quite a while), don't sweat it.
A sound card is nice, but you don't have to have one unless you are driving a large set of speakers (multiple satellites) or are a total audiophile.