Also, as a side note, the age of your camera can determine how you can hook it all up.
My MBP has one FW400 port and one FW800 port. My GL2 was not recognized when I had it plugged into the FW400 port and my HDD into the FW800 port, so I had to use my express card.
However, with my Canon XH-A1 I can use it in the FW400 port while my HDD is plugged into the FW800 port.
There seem to be a lot of little factors. As Lethal said, just try it out 😉