Hi Chris,
Do you access BBand through a STB or Cable Modem? If it is a cable modem you should be able to unplug your mac, turn off the modem, wait five minutes and then plug your pc into the modem. When you turn the modem on again it will give you a new IP. No configuration is needed whenever I do it on my modem.
However, STB's are different. I think you do the same turn off, disconnect and wait five minutes thing. However, when you turn the PC and STB back on you need to go to an url like
http://start.ntl and go through the Provisioning Screens.
Hope this helps,
Phil.