How to view MS office files online in asp.net 4.0, C# web application

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C#

C#4.0

ASP.NET4

Currently I am working on a file management system which developed in c# & asp.net
Where user can store bulk files. Now I want to view all viewable formats of file (i.e. image, ms office, pdf etc) open in browser (without downloading in clients local machine). I already done half of my job i.e. my application working fine for all image files and pdf files. But I facing problem with ms office files (i.e. xls, xlsx, doc, docx, ppt etc) formats. I tried some piece of code

protected void Page_Load(object sender, EventArgs e)
        {
            //Set the appropriate ContentType.
            string FilePath = MapPath("Test/xyz.pdf");
            Response.Buffer = true;
            Response.Clear();
            Response.ClearContent();
            Response.ClearHeaders();
            Response.ContentType = "Application/pdf";
            Response.AddHeader("content-disposition", "inline; filename=\"" + "xyz.pdf" + "\"");
            Response.Write(FilePath);
            Response.End();
        }

This code works fine only for .pdf files but when I changed my content type Response.ContentType for word or excel files Application/msword (for Microsoft Word files) Application/x-msexcel (for Microsoft Excel files) then this code not works. Please guide me what can I do. Should I use any tool like google documents viewer or some thing else.If it is possible only with tool then please suggest me a good tool for this.

Thanks in advance