While the transition might be exceptionally painful for those using micro ATX cases, PCIExpress is a good thing. If it weren't for new advances in ports, we'd still be usising ancient VSA ports (or worse!). PCI express will not only replace AGP slots, it will, of course, replace PCI slots. Although I don't have any official specs on hand, the speed improvement will be quite nice.
Of course, as it's a new technology, I can imagine it will be quite expensive. Fortunately, it will probably be possible to wait out the first year or so of PCIExpress, given that we could live with slightly dated technology. (We would still be able to upgrade our processors without changing motherbaords, we'd just be stuck with older 3D cards)
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Nes digs around in the trash can.
Nes finds a hamburger!
Nes puts the hamburger in his backpack.
Wake up, George Lucas... The Matrix has you...