Quicktime works in IE7 but not Firefox2?

I have made Firefox2 my default browser. Quicktime works in IE7, but not in Firefox 2. I know this because I was sent a link to a webpage with background music, and when I viewed it in IE7, it played, and when I viewed it in Firefox2, a bar displayed saying "additional plugins are needed to display all media, click here to install missing plugins." and when i clicked, it says "no plugins were installed" and gives me the option to manually install. when i click manually install, it sends me to the apple website and the download page for quicktime -- but i know i have the most up-to-date quicktime -- i can open the player and check for updates. I don't know how to tell Firefox 2 that I have quicktime!