AMD nor mobos' manufacturer haven't confirmed Barton compatibility with today's mobos, but it seems it will be.
In fact, is the most logical assumption. Probably a great percentage of Bartons sold will be to people with Tbird, AXP and Tbred looking for an upgrade and to enlarge mobos lifespan. Also, in theory, there will be only some months between Barton and Hammer, so I think people that will be thinking in building a new computer will wait for Hammer (it will be worth, they will take advantage of new socket, chipsets, etc.)
Also, from the technical point of view, Barton is just a Tbred with 512 instead of 256, no changes in core, so I suppose each mobo that todays support Tbred will support Barton.
A new BIOS could be needed in some cases, but that's all.
Hope this helps.
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