You most likely have a very old version of Java. Uninstall your old version of Java (Start, Control Panel, add remove programs) and then try to install the newest one from http://javadl.sun.com/webapps/download/AutoDL?BundleId=63691.

You are also running a very very ancient version of Firefox that has many known security holes. I would upgrade to Firefox 12 ASAP to keep your computer more secure (Windows 2000 is an insecure OS anyway, but any bit helps)

You also should know that Mozilla will be dropping support for Windows 2000 when Firefox 13 is released. Firefox 12 will be the last version of Firefox to receive any updates. https://support.mozilla.org/en-US/kb/firefox-no-longer-works-windows-2000

This is a very old machine so if something bad happens to it-no great loss. Various software components nag me to upgrade them, but invariably they fail because they won't run in a W2K environment. It would seem reasonable to check first and nag second. All this is by way of saying the current release of Java won't install on this device.