In Windows XP, you can connect 2 computers using FireWire adapters, which is why Windows might call a FireWire card a 1394 net adapter. Since FireWire is not a commonly used inference, you may wish to remove your IEEE 1394 to make room for other PCI devices.
1). Turn off your computer and unplug the power cord. Use a screwdriver to open your computer. You should be able to open the case by removing a few screws on the back. Normally removing the left side cover will grant access to the motherboard.
2). Locate the 1394 net adapter. It should be plugged into a PCI slot, the parallel slots in the bottom and back of most computer cases. Look on the back of the case and look for the card with FireWire ports on the back. FireWire ports look similar to USB ports but are slightly smaller, and 1 side of the plug has 2 sloped edges, making it a hexagon rather than a rectangle.
3). Unscrew a single mounting screw which holds the card in place. The screw should be readily visible, near the back of the case on the inside. Remove the card. Grab the card firmly with both hands on either end or pull it straight from the PCI slot. Close the case and reattach the power cable.