hey I have a question, when I host a web page and try to play an avi file it plays it with quicktime, is there a way to that same file play with wmp? thanks

by the way I need it to work under firefox

You dont provide any details about your code, so it is hard to say what is wrong.

First of all, I think you are using the <embed>-tag, wich is not part of HTML or XHTML, but only supported by internet explorer and netscape. You should use the <object>-element instead.

If you are using the object-element, (or the embed-element), you should know that the browser (client) decides wich plugin should be loaded in order to handle the media (or other) data that is linked with the object-element.
You can advise the browser however with the atrribute 'codeType'. Set the value of this attribute to a specific mime-type:
http://www.iana.org/assignments/media-types/

Dont forget to include some code between the object-elements to provide information to browsers that dont support the object-element like:
<object codeType="application" data="file.avi">
<p\>Sorry, you're browser doesnt support objects\</p>
</object>