PCI Express is supposed to replace PCI (and AGP, since AGP was built solely to give graphics card more bandwidth than they were getting in PCI slots). The next-generation of nVidia and ATI cards will supposedly use PCI Express, but have "converters" of some sort to make them compatible with AGP (8x I would assume, maybe also 4x) boards so everyone won't need a brand new mobo to use the new cards. Pretty much everything can use PCI Express, but with mobos coming with 8 USB and 4 Firewire (or whatever number of these), sound, dual SATA RAID, and LAN integrated, and the slow but almost there elimination of legacy ports (PS2, parallel, serial) graphics cards and about all you'll see in them. I could see TV tuners (but media PCs have these integrated) and modems (HAHAHA...oh, sorry to those of you still on dialup), but I can't think of any other need for more than one expansion slot in future consumer computers. Many think that within two to three years the efforts of Shuttle to show that a mini-ITX (or whatever that form factor is called) board can support a viable gaming system will push mainstream and gamer users to these size PCs, which only have one or two expansion slots physically possible, and only servers will need the added slots for multiple RAIDs or whatever.