Ok guys it's me again here with some questions for my grandpas computer. Were going to build it togther he is a hard core gammer........IM SERIOUS!! IT'S SWEET!..... well any way I was talking to him about PCI-E and he has agp. I found this sweet stuff for him. Its a Asus A8N SLI Deluxe nVidia Socket 939 ATX MotherBoard and an AMD Athlon 64 3500+ Processor. With a eVGA GeForce 6800 GT / 256MB DDR3 / PCI Express / SLI / Dual DVI / TV Out / Video Card. Hes gona get one card now and then 1 latter to compleate the SLI. I checked the ram speeds and stuff and all his other stuff of his p4 mobo should work on this mobo right? and also ATX is the size of a mobo right? so this should fit in his current case?