WebBrowser Control Dotnet Office 2007 Problem

I am using Vs 2005, Office 2007 and Windows XP. When I try to open any office document in WebBrowser control, it opens the whole applicaiton. I want it to be embeded in the control . I have used following code.
string x = “file:///” + @”L:/temp/Presentation1.pptx”;
Uri ur = new Uri(x);
webBrowser1.Navigate(ur,false);

Thanks in Advance
Himal