Secunia

This is a free on-line scanner i have used for years for checking if things like if Java is out of date, Secunia wont download or install updates but it will tell you what is out of date and provide a link for you to update if you choose. There is also a reminder service if you want to use it.

Secunia > http://secunia.com/vulnerability_scanning/online/

Yep, this is one of the applications that I always install on any PC of mine. It is an invaluable tool that every PC savvy person should use (IMO)

It has a pretty large database of vulnerable applications, and helps you know when to update things like Flash, PDF Readers and other common methods of infection.