Firewire is for external burners that can be used for both PC and MAC and you will need to fit a Firewire PCI card if your PC/MAC doesn't have one. Firewire has a very fast bus speed (400 MBit per second compared to 66 for a UDMA-66 HDD) but the bottle neck with CD burning will always be the speed of the writer. Thus, unless you want to share your burner, I would upgrade your internal drive to the fastest you can afford and wait for the blank CD manufacturers to catch up with you (as sft42 rightly says you are restricted to the speed at which the media can handle being burnt).