<<< However, when I check the status of the Local Area Connection in the icon tray it reads 100.0 Mbps, it should read 400.0 Mbps. How do I change this?>>>
You have a 4Mbps connection with Blueyonder, not 400Mbps!
The 100Mbps speed indicated is the speed at which your ethernet connection is running, i.e. the speed at which the connection between the network adapter and the cable modem runs - it is not the speed of your internet connection with Telewest.
<<<there are two 1394 Connection icons, both of which read as 400.0 Mbps speed but no activity!>>>
These are Firewire connections, which are probably not in use, unless you connect an external hard drive or video camera by Firewire. It is normal behaviour for them to show as "connected".
<<< Also, when checking the activity status it is read in packets rather than in bytes, again any way of changing this??>>>
Not that I'm aware of. Why is it of interest with an uncapped broadband service? There are third-party applications to monitor the amount of traffic transferred over a network connection.