Core 2 Duos are excellent indeed, however Core 2 Quadro will be two Core 2 Duos in the same package, and it's sucks too much power (similar to the Pentium EE 965).
It will be pure horsepower indeed and a multitasking beast but it will be too expensive and power drainer.
I would like to swittch to a Core 2 with my next upgrade, however I still have 2 256 Mb DDr400 sticks from my old fried system, so I'll use them and add two two 512 mb sticks more to it. DDR-2 is too expensive at the minute. So the most probable thing is that I'm going for a AMD64 Dual Core solution.
For those waiting for the AMD K8L quad core processor coded Barcelona, it will be released until H2 2007