Firewire 400: (6.88 gigabytes) / (400 Mbps) = 2.34837333 minutes
Firewire 800: (6.88 gigabytes) / (800 Mbps) = 70.4512 seconds
USB 2: (6.88 gigabytes) / (480 Mbps) = 117.418667 seconds
You're not going to get full bandwidth (I think the hard drive in the iPod is actually the bottleneck), but there's an approximation.