PCI-X? that's never going to become mainstream. Now if you're talking about PCI-e, that'll become mainstream in prob 1-2 years. currently, BTX sucks (not worth spending $100 for a new case and psu for a decrease of a couple degrees), pci-e fares off worse then agp, and ddr2 is crap compared to ddr. atx and agp will not die out that fast. heck, the most recent pci video cards are the fx 5200 and the 9200.