Re: lookin for some suggestions
For the Core 2's you'll need to upgrade your DDR to DDR2. RAM is cheaper now than it's been for a year now, so that's good news.
In terms of mobos it depends on if you want an OC, SLI, and what vid card you are matching up to it.
I'm pretty happy with my 965 chipset P5B-E, but it has it's issues and there's only one PCI-E slot.
It sounds like the 650i's might be a more stable alternative to 680i's, but you'll hear different things from different people. It's probably safe to say that you'll have to update the BIOS on almost any mobo you get.