As mentioned Aegia Physics cards are a total waste of money at the min as no software supports it yet (Well hardley any). I should imagine in a years time they will be really big once software support them.
Also as mentioned two of them Nivia 7950 GX2 cards are a total waste of money too just the one will do the job or to ATI X1900s in crossfire.
Unless your using Windows pro 64bit I would not recommend using 4 Gig either as the 32 bit version is supposed to support upto 4 Gig but it does not do it very well at all and you will have loads of problems from what I have herd.
If your after performace I am supprised you have not picked the Western Digital Raptors for HDDs. They are noisy but hey with that PSU and top end graphix cards wirring away your not going to hear them anyways.
Also me personally I prefer Asus boards for Intel rigs too.