My internet provider has an elaborate system in place to screen virus' and remove affected posts.. should I feel safe with this precaution and NOT get additional Virus protection software for my computer?

You're not completely covered. It's true that the most common source for viruses it through the internet, but it wouldn't protect you against everything. Virus programs that reside on your computer are still a good idea because it will protect you from viruses that get onto your computer from a floppy, CD, or other media. I also have a hard time believing that an internet provider can completely protect you from viruses that are hidden in things like media files that you download. If one does get past your internet security, a program like norton will catch it and quarantine it.

I don't know if you've ever had a virus before, but if you have, you'll know that you could just kick your self for not taking the extra precautions when you had the chance.

I resoundingly second Bill's opinion. Another advantage of running antivirus software is that it can alert you to "virus-like activities", and stop them in their tracks.

Synantec's Norton Internet Security 2001 (last year's release) is widely discounted to about $20us, and includes a capable firewall, antivirus with email scanning and script blocking, plus a year's worth of free updates (updates are available once or twice a week). I very much recommend it. Just remember to run LiveUpdate repeatedly after installation to obtain all the updates.