Supposedly, all Socket 939 boards will support AMD's dual core processors once they come out. Unfortunately, only Intel-based systems offer mobos that support both PCIe and AGP. That would be VIA's PT880 Pro, which supports both DDR and DDR2 as well as PCIe and AGP.
My understanding is that Via Technologies will put forth their dual AGP/PCI-e chipset for AMD called -- and I'm going by memory here -- KT890 (I definitely have the digits right). I read a review of a sample board and the conclusion of the review is that it pales against the NForce4 chipset. Worse yet is the misleading promise of dual graphics processing when in fact there is no splitting up of the screen or of alternating lines for gaming; they only really
mean that the AGP part gets its own monitor and vice versa. Also, in fact, Uli will debut what they tout as "TGI." I guess by this they mean "total graphics integration", but I don't know. Their solution, and it'll be available for AMD, will offer AGP/PCI-e, and they want us to get excited by this: that you can also plug into a regular PCI slot a butt old graphic accelerator; hence, "TGI." This offering will be available by June sometime. I do commend Via and Uli for offering a bridging motherboard for those many people who ran out and bought themselves expensive NVidia and Radeon AGP cards last summer for Doom III and H-L 2 and don't want to throw away $500 cards less than a year later just to board the PCI-e train. Kudos to Via and Uli. This way, once you're ready to buy a PCI-e card, you're good to go.