With Firefox running, select Tools>Options and the "Content" icon at the top. The third checkbox down is "Enable JavaScript". Just check it (or press Alt+J) and click OK. For good measure, close and relaunch Firefox.
With IE running, select Tools>Internet Options. (You can also get here from the "Start" button, Control Panel, and Internet Options.) Click the "Security" tab; highlight the Internet icon (normally the one with the glove); click Custom Level. In the "Settings" box, scroll to the section titled "Scripting". (You may have to scroll waayyy down.) Under "Active Scripting", click on Enable. Click OK (to close "Security Settings"), and OK to close "Internet Options". If you did this from within Internet Explorer, it's best to close and relaunch it.