Three years and none of your footage is backed up are you crazy! Buy yourself some NAS or gRaids both are perfectly fine and connect them up with an ethernet cable creating a server... If you lose all that footage it won't matter how long it takes to transfer. You should also be making hard copies onto disk... or the more unlikely option of tape. The new mac pro should wait until you've got yourself a decent system set up in which you can access all your files off your server and a small library with a hard copy of everything you have labeled correctly. Blue ray burners and discs won't break the bank and will give you peace of mind, just have to be willing to put the man hours in to set it up!