I was under the impression that you needed a case... Anyways, what size case are you going to be using? I myself am a newcomer to all this stuff, It just happens that I signed up about a week and a half before you did.
If you plan on upgrading your RAM (memory), go with this
I won't comment on the mobo or processor, I have no clue there.
If you're gaming with this setup, you might want to look into a GeForce series 7 (7xxx), or if you're going with Vista, wait until the 8600GT comes out.
The Hard Drive... that's the one I like, so I'm going to say go with it ^.^
Everyone told me that I should go with 500W or more, so I can expand my system later.