To expand on how

Firefox: tools menu | add-ons | plugins | find the java plugin and click disable.

Chrome: type chrome://plugins/ into the address bar and hit enter. find java in that list and click on disable near it.

IE: (xp) start | Control panel | internet options | programs tab | manage add-ons button. find all java entries in the list and click on the disable link.

(windows 7) I don't have a vm in front of me but it should be similar to the xp instructions.