I can rule out the home network for this job - way too slow, even at wireless-G speeds. Therefore, I'm going to be using an external Firewire 400 HDD to do the copy. I've already copied the data on the source Mac to the drive. How long will I have to wait for the copy job to complete (ignoring time spent setting up the drive and getting its cables moved/connected)? The destination Mac runs Snow Leopard, and supports Firewire 400. The source Mac runs Tiger, and is PowerPC-based (it's a Rev C iMac G5, with its memory upgraded to 2.5 GB and HDD upgraded to 320 GB), if that makes any difference - it's limited to FireWire 400 only, and lacks a FW 800 port.