Security is always a balance between safety and functionality, to make things completely secure you'd need to shut your system off from the outside after all. Anyone who has ever read the BoFH knows just how terrible users are. That said I do believe in using reasonable precautions such as antivirus software and windows updates, after all it's possible for google ads or similar on a perfectly legitimate web site to contain virus code. It has happened before and it will likely happen again, not to mention the fact that windows update also plugs holes to stop programs running without user consent such as with data injection attacks and buffer overruns.

All this reminds me of a friend who was asked to help the local job centre set up supernova on their computer, they couldn't figure out why it wasn't working so they asked her help as a supernova user herself and a council employee.

Friend: Does the computer have a sound card?
Staff, incredulous: Of course not!
Friend: Didn't you read the side of the box where it says sound card required?