It won't be using any resources fortunately (well, not if your OS is well designed. I don't know if windows is because I don't have the source in front of me, unlike Linux... but that's another matter altogether), so don't take it out. If you have an mp3 player (many support 1394), DV camcorder, some digicams, or a firewire external enclosure, yes, you too can benefit

Also, some internal components now use firewire (there is at least 1 firewire internal DVD+/-RW), these can usually be attached on the inside of the card as to avoid wire clutter.