For me, I've mapped a network drive ( a kind of virtual hard-drive disk ).

Simply go in Windows Explorer ( in a folder), click on tool and Map Network Drive. Enter \\192.168.(your IP adress) \My documents ( or the folder where all your files are located ). Make sure all your firewall are disabled. For a faster transfer, use a cross-over Ethernet cable ( withtout passing by the router ).

For your hard-drive that you want to erease, I think you can do this with Symantec Partition Magic ( or Partition Tragic ... sometimes it works, sometimes it only make a mess on your hard-drive. I've lost everything one time with this software ... God bless backup DVD's !!!!! )

Sure, the external hard-drive is the simplyest way to transfert datas... my opinion, of course ...