What makes you say that, the program I use from them has detected and fixed problems here at work that AVG, kaspersky or Norton didn't detect.
But anyway, as far as I know my home computers have never had any problem with viruses, everything runs very well, I also format Windows ever 6 months so that may help
If you haven't done so, try Avira, it has probably one of the best detection rates with few false positives. With Trend Micro it may have been picking up false positives or not, dunno. I'm not sure if their site is back up and going yet but take a look at
http://www.av-comparatives.org/ they do independent tests on a lot of major antivirus software. - I know off topic.
Mac is based on Unix, Unix is what Linux is derived from.
Mac = secure system files = Unix/Linux (we'll say Unix in this case)
Windows = Unsecure system files = $100 bill laying on the ground - which means anyone can do what they want with it.
Think about it if Windows secured down its critical system files, got rid of the registry, it'd work a heck of a lot better. Mac uses PLIST files for its info, which is like the registry just XML based. So let's outline the problems with Windows:
Filesystem = NTFS, come on really?
System files = still able to edit some as a regular user
Registry = very easy to get into and mess around with which crashes the system
Firewall = External 3rd party one needed otherwise let the hacking begin
Services in the registry = seriously do I need to explain this one
Unix has a better design with its services, they're located in /etc/init.d for Ubuntu. Looks like M$ needs to take OS design 101 again.