1. Get a different PCMCIA card with 2 or more firewire ports and connect the DVD burner and external HD to their own port (which leads into my next question).
2. Plug the hard drive into a USB 2.0 port on my laptop, let the DVD burner have sole custody of the firewire port (I tested this method and it works fine, I just dunno about keeping my HD on a USB 2.0 port rather than on a firewire port. Plus, I like being able to come home and just plug in my cardbus and have it done with, no messing with a gazillion wires and such).
Does a cardbus even communicate with a laptop fast enough for this to even be worth it? Is a firewire port on a cardbus going to be slower/less reliable than a firewire port built into a motherboard (or even a PCI card on a desktop)?