Secunia Personal Software Inspector
IMPORTANT: The web-based Secunia OSI service has been discontinued. We now recommend the Secunia PSI application for Windows PCs. The FileHippo update scanner is also an excellent alternative.
Secunia's free PSI service scans your computer for vulnerable versions of common software, including Windows, Java, web browsers, Adobe Flash and Adobe Reader.
The PSI scanner installs itself as a pair of Windows services and configures itself to stay running in the background, checking for out of date software. The scanner is a Java application, and seems to be somewhat resource-intensive, so you might want to consider configuring it to run only on demand rather than having it scan continuously. Once PSI is running, click 'Settings' at the bottom of the main PSI dialog. Disable 'Start on boot'.
We recommend that you configure PSI to only notify you of available updates and not to download and install them automatically. In our testing we have found that PSI is somewhat over-eager, and may install updates that you don't actually want. Once PSI is running, click 'Settings' at the bottom of the main PSI dialog. Enable 'Detailed view', and open 'Update handling' and select 'Notify'. You should do this as soon as possible after starting PSI for the first time to avoid problems.
Another way to avoid unwanted updates is to configure PSI to ignore specific software: right-click on an entry in the list of installed software, and select 'Ignore updates to this program'.
As of 2013Nov04, the current version of PSI is 3.0.0.8013. Unfortunately, this version has some issues that cause it to run extremely slowly and unreliably, so we recommend version 3.0.0.7011, available for download from this site.