You know, all these guys have given you some great advice.
Here is my $.02.
Here is the best "air" cpu cooler at the best price:
http://store.yahoo.com/svcompucycle/xp90-ret-21.html
Get a good 90/92mm fan and you are set. This is recommended by Angry_Games at DFI Street.
You can go for an Opty, but none of the mobo makers will officially support them. This is because AMD won't allow it.
As for memory, "value" of any brand is questionable. You say "everything A+"--- don't ruin it by buying cheap memory. It will come back to haunt you.
Also, you say you are not going to OC, but you are buying the chief of OC'ers -- DFI. So, you will no doubt change your mind soon.
I would agree with the suggestion to buy the Ultra-D. You can still use your X850XT or any other card, but since you are not going to use SLI, take the money that you save and buy your sound card.
One last tip, if you haven't visited DFI Street,
http://www.dfi-street.com/forum/index.php?
then you should. Great help for your DFI board.