I have a similar problem as the OP. I will need to transfer tens of gigs of data from my Powerbook 12" to my new Macbook (once I get the Macbook, with the expected delivery date being 5th November). The Powerbook has no gigabit ethernet, so I will be stuck with the slower transfer speeds of 100Mbps ethernet.
Now here's the wrinkle. My Powerbook has only 40GB of hard disk space, so I have backed up a lot of less frequently used data to an 80GB Lacie external disk (including my 15GB iTunes music collection. Imagine living without music for the past several months. That's another reason I am so waiting for the new Macbook to arrive). Anyways, that's a Lacie FIREWIRE external disk. So I can't connect it to my new Macbook.
Is there a way to connect the external drive to my Powerbook and then directly copy the data via Ethernet to the Macbook?
I suppose this will involve exporting the the drive as some kind of network share? Because the alternative - copying a chunk of data from the Powerbook to the Macbook, deleting it on the Powerbook, copying another chunk from the external drive to the Powerbook, copying it to the Macbook, lather, rinse, repeat.... is almost too painful to contemplate.
Any help on the bold part above would be greatly appreciated.