Anti-virus software is becoming so bloated and inefficient, it is becoming a security risk itself. The situation will only get worse on Windows as the footprint of AV software continues to grow.
As other OS grow attacks on them too will become more common. With Windows though there has to be a balance as to what is practical and what becomes overkill. Hackers and Virus creator simply look for large targets. The largest user target now is WINDOWS.
BTW Micro Trend also gave my Firefox Browser a fit. Seems I had several problems and Micro Trend created quite a lot of them. I'd like to have Super anti-spyware back but SPYBOT is doing a pretty good job keeping things out.