They are about as fast as the internal drive of the powerbook -- I think faster than an external firewire drive, but I haven't really done much testing of that. Plenty fast anyway. You can take one apart and put a larger drive in -- I bought a 6GB model cheaply and put a 40GB drive in. The only hard part is removing the sticker on the back of the drive -- it leaves some residue behind. As long as you don't pay too much, they are very handy.