I agree with Wabe. Save up your money and get an Intel Mac. They will render 5 to 6 times faster-- probably more, than your eMac. Even the Mac-mini will render much faster. I have both Macs and PC's, and my old Centrino Mobile laptop rendered over 2X the speed of my G4 Mac.

You can check out Frederic Louguet's website regarding rendering speeds.

Though I see it doesn't even mention the non-intel Macs.