i would suggest what mee987 said first... check device manager for unknown devices and install the driver if so.
btw, is the sound card you're installing a sound blaster audigy by any chance? if so it will always add the 1394 adapter to network adapters since you can have a 1394 lan connection. in my xp network connections, i bridged my 1394 and LAN connections together so i won't have to disable the 1394.
also like csoup said, it might be a good idea to remove the sound card, try to get your nic working first, and if it works fine, then add your sound card later.