i'm looking to updrade from a power mac g4. looking to either go w/ the older power mac dual or the newer dual core models. for motion, i don't think processor matters as much as video card, correct? i'm wondering how well the best pci-x video card compares to the 7800 pcie for the dual core macs? will workflow be more benficial if going w/ a pci express mac compared to a pci-x machine w/ the best video card in it? thanks!