Please don't key on the browser name (User-Agent) for this
functionality. The HTTP protocol has included a facility for
format negociation for several years. I hear the Apache group
has implemented it in their revision of the httpd 1.3 server.
Some folks are working on a draft that explains format negociation
in detail... sorry it's not available. For now, please
see the http spec:
http://www.w3.org/hypertext/WWW/Protocols/HTTP1.0/HTTP1.0-ID_38.html#HEADING112
Dan