Maybe you have read about the latest ranking algorithm changes on MSN Search in online forums.
It seems that on-page factors are now more important and that MSN Search prefers web pages that are listed higher in the web site directory structure (www.example.com/widget.htm is preferred over a web page that lies deeper in the directory struture: www.example.com/widget/green/large/widget.htm)
It also seems that MSN Search likes static pages better than dynamically generated web pages.