Complex Web Content question

Hi,

I need to find a solution for managing a website that have different versions of its pages. For example, a home page has 5 versions (templates) to accomodate 5 types of user. The boss wanted a web application that can generate 5 templates dynamically, so that web authors do not need to create 5 versions of a HTML page. What technology would allow me to do this ?
I know that you can use XML and XSL to generate dynamic HTML templates. But the thing is by using XML, you have to develop an application that would parse the existing HTML pages, put XML tags, and use XSL to generate the templates. Parsing and putting XML tags into the HTML pages are very tedious (even with codes) since the HTMLs contain tables, td, etc...Also the number of our existing HTML pages are huge.
What about CSS ? CSS can generate different contents...but hiding Source Code can be a problem. We have different templates so that different types of user only be able to view his/her content. With using CSS, can we hide the Source Code from our users ?
I heard Microsoft Content Management Server. Would it able to convert existing versions of a page into just one version, and generate 5 templates for them, dynamically ?

Thank you for your help,
john b.