I would recommend this exact same setup. I am currently using a dual 2.5 GHz. G5, nVidia 6800 Ultra (with 30″). I am using the Sonnet Tempo-X 4+4 right now, but I will soon switch to the Sonnet Tempo-X eSATA 8. I am also getting the Multibridge Studio when available. I am using the Firmtek SeriTek external SATA enclosures. Just don’t use either the Maxtor Diamondmax 10 300GB SATA drives, or the Maxtor MaXLine III 300GB drives with the Sonnet cards. There seems to be an issue with these drives and a chip used on the Sonnet cards. I would recommend going for the Seagate Barracuda 7200.8 400GB SATA drives. Can you think of another PCI card you would also need to use? I couldn’t, so I’m not worried about having all slots filled…