Spec looks good, im using vista 64 primarily now 2 gig is fine for most things, some games like company of heroes can thrash the hard drive a bit when exiting to windows.
The ultra is really not worth the cash over the regular gtx, might want to pick up an evga 8800gtx and use their stepup program to get the 9800gtx when thats out.
http://evga.com/stepup/default.asp
Sound card probably isn't needed, the integrated audio on the p35 is pretty decent.
Ram im using is the following OCZ 2GB (2 x 1GB) PC2-8500 1066MHz "sli ready". How ram can be sli ready is pretty funny, marketing gimmicks ftw.
Might want a decent cooler for that quad, they run pretty hot, stock coolers definately not worth a shit. thermalright 120 ultra extreme is meant to be the best (have to buy fan seperatly) i had one and it had a concave base and wasn't worth a shit, if you cna get one without the concave base theyre supposed to be really good.