I would go for a P35 board, Q6600 cpu and 8800 GTS gpu with 2 gb DDR2-800 standard ram (OC ram would require higher voltage).
Nice choices, that. I'd be a little leery of the 8800's with the issues people have been reporting with them, but I'd probably still go with them as they'll be the best choice overall once they get those issues totally ironed out (Not to mention that you'll be able to pick up all the ARB extensions to provide the DX10 capabilities once NVidia finishes that support- newer titles (Read: Rage...) will most likely USE them if they're there...).
However, I'd shy away from an ECS manufactured P35 board as they are a little less fussy about components, etc. and their motherboards can tend to be "twitchy".
Good choice, the diff between those too are only the number of PCI/PCI-E slots. As Crossfire is only working with Windows [and there is NO SLI support with P35] and you only need one PCI-E slot and can go for GA-P35-DS3R, then you gain one PCI slot. If you don't need more than 2 PCI and you to have it for future PCI-E cards get the GA-P35-DS3P.