I guess I just haven't seen trustworthy core 2 duo base systems that have "real" motherboards... it seems like all the good core 2 duo mobos that have quality integrated parts and also have some expansion slots are very expensive.
That said, the linky to that goofy cross-dressing mobo we posted about a month ago was very interesting. sub-$100 for a board that supports AGP, DDR, and DDR2 memory...
I dunno. It comes down to how much performance and upgradability you can get for your $$$. If you can find a core 2 duo system with the same generic specs (same amount of ram, same HD size, same vid card, etc) and the same price, then the core 2 duo system is probably a better deal. I just haven't personally seen any of those that I'd trust. Dell has value core 2 duo systems but you don't get a pci-e slot or a standard case, mobo, sound card, or power supply. In my 20 years of PC building experience, there is nothing worse than a dell branded OEM sound card... Those things are absolutely horrible no matter what they call them. A "soundblaster" purchased from Dell is NOT a real soundblaster. It will have crappy amps, reduced quality processors and capacitors, will be flat-out missing signal processing components from the PCB, and the firmware/drivers will be severely crippled so you can't even install updated drivers from creative after Dell quits supporting the card.
Er... my point being that in my experience, I haven't seen a single $750 Core 2 Duo system that I'd care to own, but you can find many $750 AMD systems that have really nice components that are upgradable. Maybe you've seen stuff that I haven't, but I also don't bottom-feed when I go looking for my next upgrade