<<< The computer says my 1394(?) connection is 400 Mbps >>>
That is your "Firewire" connection, which does have a nominal data transfer speed of 400Mbps, but Firewire has nothing to do with your internet access.
<<< and my wireless network connection is 54Mbps, is this normal or can I speed it up any? >>>
54Mbps is the data transfer speed of 802.11g Wireless Networking hardware. This is still very fast in relation to the relatively slow speed (in networking terms) of your broadband connection. Unless you have an extremely bad wireless connection, the Wireless Adapter itself won't be having an adverse effect on browsing speeds.
If you want to check your broadband connection speeds, have a look at - click here