MBSA

MSBA is free so why not. It's based on Microsoft Update and finds any security misconfigurations and missing security updates on your machine. I have not used it, but if you think you have holes in your PC's security, give it a try and let us know how it works.

Link to download :

http://www.microsoft.com/en-us/download/details.aspx?id=7558

I used this program for a few years on several standalone networks, i.e., the computers had no link to the outside world.

The biggest pain was in downloading and distributing the patches which MBSA recommended. I scripted the installation of each patch so I could distribute to several users of distinct networks.

If you are connected to the Internet, Microsoft's automatic updates are the way to go. MBSA is just the manual way to perform the same task.