Thanks SO,
USB2 is the 2nd generation of USB- much, much faster than the original USB, and a bit faster than Firewire. I just am not sure whether it's possible to connect from DV to USB2, rather than Firewire- I don't want to buy an expensive cable and then find it doesn't work! Or vise versa- I don't want to buy a Firewire card if it's not necessary!