Believe it or not, most people feel that it's better to pay than to get something fixed for free and they don't even try the free one. We understand that MS stuff are known to be flawed in many ways, but we did try the MSS (Microsoft Security Essentials) and they did work. One of my friends computer were infected with tons of virus, on the screenshot you can see... ... the porn pictures icons keep popping up on the desk top. We down loaded the MSSuseful, installed it and it does work, the McAfee on the system tray is just sitting there looking pretty while other viruses and adwares popping up all over the place.

Spybot - Search & Destroy 1.6.2

We leave it at resident in the systray

And when it's in action

This one does monitor changes very well. We even turn off the annoying Windows 7 UAC.