Make sure you have the latest version of Trusteer Rapport which has been updated for Firefox 4, you just need to run the setup file and the icon should appear. For details see http://www.trusteer.com/faq/i-dont-see-rapport-icon-firefox-4

Thanks TonyE, did all that but the icon is still not visible in the browser. Checked to see if Trusteer Raport is working and it is running okay, but still no icon? I assume the icon (green bg with white arrow pointing left) appears next to other add ons in the browser (see attached image)? Any suggestions?