Go to the help button on Firefox and click on (About Firefox). I'm willing to bet that your updates has brought you up to version 6.0.2. Your download which may be version 6.0.0 or version 6.0.1 would be older.

Thanks to Lloyd.Hayes.

Lloyd, you are right, the download is 6.0.2, but still, when I place this in the Mac Applications folder, it says that a NEWER version is already there, but this is Firefox 3.6.22. Isn't 3.6.22 older than 6.0.2?

It's confusing, and I don't want to install 6.0.2 if it is indeed older than 3.6.22--doesn't seem logical, but that's what the installation process keeps saying.

Thanks for your help.

Firefox 6.0.2 and Firefox 3.6.22 were released on the same day. The actual date of the executable in each version may be a few days different between the two versions, and that is what is triggering that message from your operating system. Firefox 6.0.2 is the later version regardless of the date it was generated.