I have 1Password running on XP at work. The 1P icon shows up in Firefox 5.0, but I don't see it in IE 8. Is there some trick. I selected IE in the Preferences > Browsers window. It shows the right version of IE (Microsoft Internet Explorer 8.0.6001.18720).
Let me just add, I am a mac user at home and never seem to have any issues. At work we are made to use Windows, and I recently got a copy of 1Password for Windows. Seems to be more problematic with Windows browser.