do you have an opinion, btw, about whether I should purchase a Mac Pro or an iMac? I also do animation design using AfterEffects, and edit using FCP...

Your big decision between the iMac and a Mac Pro is expandability. With the Mac Pro you can install more hard disks, and have the option of installing extra cards in the unit (if needed). But if this is not an issue, then the iMac is more that capable with the Quad processor, and expandable RAM up to 16GB if needed.