Parse xmlhttprequest

Parse xmlhttprequest

I'm piecing together an idea to take an existing intranet site that I use on a regular basis that is not very user friendly at all and creating my own interface to cover the existing site. I've learned that I can grab the site using the xmlhttprequest but how do I parse and work with the objects once I have it? 

I would like to restructure the menu system and all, I've got the idea of what I want to do I just need a jump start on how to do it or if it can be done, which from what I've read it would seem so.

Thanks,

Brian