Help Please - Browser negotiation for xhtml

[Fundraiser]

Been working on www.nonprofit.mobi which will need to validate as xhtml-mp but I could not get the index.xhtml to render so I changed the file type to html just to test the site but will need to use a process to detect the browser and then send the correct version of the site - either html or xhtml. I was reading about how to do this at this site http://www.martinpayne.co.uk/computing/xhtml-content-negotiation/ but I just don't quite understand how to implement it. Any help with understanding what I have to do would be appreciated. Thanks,

 

[Barrucadu]

all browsers understand xhtml - but use the .html/.htm/etc file extension

 

[Fundraiser]

In order to validate for dot mobi compliance, I have to serve xhtml files to mobile browsers but I also want to have the site available to other browsers but IE tries to download them so I have to serve IE html files. It is easy enough to have two versions with different extensions available. What I need is to implement any of the fixes described at the link listed in my first post. Thanks again if anyone can help.

Rob