I'm thinking of going Broadband but I'd like some advice first. I know that this question may appear stupid but, as I know that braodband is always on, does it actually mean that? Are you able to switch off the input from the phone line so isolating the computer from the line, clicking back on as and when you need it. The thought of a computer being accessable all the time worries me, firewall or no firewall.
You will create a new DUN connection, with the broadband details, password etc. You can disconnect by clicking on the DUN icon or - if you're really paranoid - you can pull the broadband modem plug out of the splitter socket (the bit that allows your phone and the broadband modem to coexist on the phone line).
I still keep my old Abel Gratis free dial-up ISP as a DUN connection as well; it's very handy if you get a broadband 'outage', which can happen from time to time if your phone line is a bit noisy.