I'm not sure how slow your connection is but 100Mbps (100 Meg) is much faster than you can expect from any home broadband connection, the highest currently available from BT Broadband being 8 Meg I believe.
The 1394 adapter is a firewire connection for transferring data e.g. from a DV camcorder.
Why do you think it's slow, have you performed a speedtest? What were the results?