Turns out LaCie makes an excellent portable FireWire bus-powered 7200 rpm hard disk which implements a RAID 0 solution. The LaCie Little Big Disk Quadra does it all. This, my friends, is the ultimate drive for running a VM from an external drive to a MacBook Pro. It’s 7200 rpm, RAID 0, FireWire 800 and has 400 GB of total storage space. Perfect.