I would get the x800 xl, it is a lot more powerful than the 6600 gt.
It has 16 pipelines and 256mb of GDDR3 memory. It's the best bang for the buck video card on the market right now.
This is an excellent deal right here:
Also for your hard drives instead of getting one big 200gb I would get 2 80gb and RAID 0 them for a lot more speed and almost just as much storage.
Get two of these and you will be extremely happy:
^one of the best hard drive deals right now imo.
Your ram looks decent if you aren't planning to overclock. If you are I would recommend some better corsair or OCZ ram for that.
Also get the DFI board like everyone is suggesting. I guess you can't go wrong there.