I've been on the internet since 1996 and in that entire time I have been hit by a virus of some kind or another only 3-5 times. And as far as I know my computer was hacked into only around two times, but that was before I started running a firewall. I highly suggest that you run a virus background scanner AND a firewall (Not blackice though, yuck!). You need this type of protection even more on a connection like cable, dsl, or any that are always on. If you're using a modem, you're not as badly targeted and probably could get by with just a manual virus scan on occasion. Whether you run virus-firewall software or not, you should ALWAYS keep your operating system as up to date as possible!

Anyway, that's just my two cents.