Firefox addon problems

I look after a couple of web sites, and occasionaly add mp3 audio tracks.
IE works fine, Opera works fine but Firefox tells me I need add ons, which it can't find. Although I search for addons manualy, and install them, firefox still can't find them. Why can't Firefox just have these as part of the package, as the other browsers do?

post a url to test
most embedded sound files should play without plugins in firefox
I found a site that played mp3 fine
I have flash and shock plugins
I use quicktime alt never added as plugin works fine
check version of firefox I use 2.0.0.4
Why can't Firefox just have these as part of the package, as the other browsers do?
so user can set it up they way they want
and it's free the one's you mention have a cost
mp3's and other embedded stuff can carry spyware
even bad script can lock up a browser
by far as for me the best browser is firefox

The most current version of Firefox is v2.0.0.11. Two current security updates have been made between v2.0.0.8-2.0.0.11. It's important that you get them. There have been a few problems noted with the last 2 updates.

If Firefox requires a plug-in that is not currently on the machine, you will usually see a message to the effect that ;"irefox has prevented an option from starting up to protect your system;". There should be a "Options" button to the right of the message, where you can click to allow, within any of the three choices. Doing that should allow the plug-in to function