Antivirus software screws up a system just as bad as virus's, plus they don't stop all virus's. I do all the MS updates and it seems to keep me safe enough. Not irresponsible, just common sense. Most people just buy anything the manufactuers tell them they need. That's irresponsible.
If your AV software is "screwing" your system "just as bad as viruses" you have bigger problems with your computer. I have never, ever, had trouble with AV software screwing up my computer worse than I've seen a virus screw up a computer. I don't buy AV software because the manufacturer tells me to. I buy it because I have been involved with computers long enough to know that it takes
one virus
one time to destroy everything. Yes, you should back up. Yes, you should keep all patches up to date. And yes, you should have common sense. Anyone who relies on one tool in an attempt to stop multiple threats is irresponislbe. Even if your computer doesn't exibit signs of trouble, that doesn't mean your computer hasn't been infected by a trojan for example. One that simply uses your bandwidth to launch attacks on other computers. I don't rely on my AV software alone to protect me like it's some magic sheild. It is a part of my security, along with a hardware router, a software router (to monitor what tries to use my bandwidth) and spyware tools. Do whatever you want. I don't care really. I know I am far safer with my combination of tools than just your "common sense".
\Dan