I would recommend getting an enclosure with USB 2, Firewire 400/800, and eSATA interfaces.
I now have the drive in hand but think it's a SATA drive even though, when I enter the G5 serial number at Apple, their site says that the G5 came with an ATA drive. I've looked at pictures on line and this definitely appears to have the SATA connectors - a 15 pin and a 7 pin side by side.
I thought that SATA didn't become more widely used until 2006. Could it be that Apple was using some SATA drives earlier?
And...my new machine has a 400 Firewire and an 800 Firewire but there is no indication which is which. If the drive is only 400 does it care whether it's plugged into 400 or 800?
ryck