Verify your Java version – eWorks - Support

There are lots of applications and websites that will not work unless you have Java installed, and more are created every day. Java is fast, secure, and reliable. From laptops to datacentres, game consoles to scientific supercomputers, cell phones to the Internet, Java is everywhere!

(from http://www.java.com/en/download/faq/whatis_java.xml)

Should I uninstal older versions of Java?

We highly recommend that you uninstal all older versions of Java from your system.
Keeping old versions of Java on your system presents a serious security risk.
Uninstalling older versions of Java from your system ensures that Java applications will run with the latest security and performance improvements on your system.

(from http://www.java.com/en/download/faq/remove_olderversions.xml)