Security firm Secunia has just released the first official version of their Personal Software Inspector. This application is a free version of their Network Software Inspector, and will scan a personal computer for necessary updates:

The Secunia PSI is an invaluable tool for you to use when assessing the security patch state of software installed on your system. It constantly monitors your system for insecure software installations, notifies you when an insecure application is installed, and even provides you with detailed instructions for updating the application when available.

The great thing about this application is that it is vendor independent; it will scan your PC for installed applications, and warn you if any of them are out of date or end-of-life. You can think of it as a Windows Update on steroids; for more information check their FAQ or the screenshots