Here’s another security scanning package. Secunia PSI will check your computer via scan, then on the fly, for known insecure software and programs that have passed their end-of-life (i.e. no longer being updated) and are therefore considered insecure. By default, the program will only report programs that are "easy to fix" and this is 100% accurate. In most cases, all you’ll need to do is click the "Download Solution" button and run the downloaded update.

I’ve got to say, I thought my new home computer was secure until I ran this program. It’s now 100% ok on the easy level and 98% on the Advanced level. (In some cases fixing an advanced problem will actually break some older software so you’ll probably never be perfect.)