It is faster.. not as fast as they advertise but it is noticeably faster.
Frees up the telephone line which is a plus. You're connected as soon as you turn on the PC and it works better with proxy servers. That is, if you want to have more than one computer connected to the internet, broadband cable seems more efficient than a regular ISP.
There are two main types: ADSL and Cable broadband. I have the latter because the Foxtel cable was already there and ADSL wasnt in the area at the time. I'm told ADSL is slightly better again but I don't know. It would be a good idea to ask.
I have Telstra BigPond (Optus are not in the area) - its about $75-80 per month, which about $30-50 more than an ISP dial-up account. Keep in mind that you're not paying for a phone call when you go online - with disconnections and so on, that can run out to $30 per month just by itself. So in reality, Broadband isnt much more at all for the regular user.
It works well for my household because we need the phone line to be free and we have more than one computer utilising the same internet connection via the proxy server.
As for ther viruses... that's probably right because of the increased online time. Leave your computer on all day and you'll probably be connected all day. I have Norton anti-virus in the system and it seems to deal with things well enough but I'm always careful not to open unsolicited attachments.
Generally, I don't have problems with viruses but I do notice more 'spyware' invading my system and slowing it down. There are ways to deal with this... I recently used a program called 'Ad-aware' and it located and scrubbed all the spyware. The worst offender seems to be 'Gator' who come in uninvited and send in all sorts of data gathering crap.
Hope that helps.
btw, broncaz, welcome to the forum.