The Java updates contain stability, compatibly, and feature updates, which are useful, but they also contain security updates. Java is such a big application, used by so many people, that it is a prime target for hackers to find security vulnerabilities. Also, it is just a perfect, perfect program to hack a computer with, with relation to the style of coding that is required to make it work. If you do not have the latest version of Java, you open up a big security hole in your entire computer, which can now be hacked. By hacked, this could be an infection, an information stealing backdoor trojan, or somebody else taking over control of your computer. The other program just like this is all Adobe programs.
Best start updating Java and Adobe programs (and antivirus, Windows, Office, Visual Studio, SQL Server, and Live Messenger) in particular.
Richard
