Convert word document to text using c# running ASP.net

I have a web application built using c#, asp.net.  I need to convert an uploaded word document to a text string.  I have looked at microsoft.office.interop.word (which works locally), but when I run on a server (where word is not installed) it doesn't work because the DLL is not registered.  It there another method of accomplishing this task?  OpenXML?

Here is code I have worked with thus far:

        public string convertWordToText(string fileName)
        {
            try
            {
                object missing = Type.Missing;
                object readOnly = true;

                Microsoft.Office.Interop.Word.Application application = new Microsoft.Office.Interop.Word.Application();
                Microsoft.Office.Interop.Word.Document document = application.Documents.Open(fileName, ref missing, ref readOnly, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing);

                string text = document.Content.Text;
                ((Microsoft.Office.Interop.Word._Application)application).Quit(); //cast as _Application because there's ambiguity
                object saveChanges = Microsoft.Office.Interop.Word.WdSaveOptions.wdDoNotSaveChanges;
                ((Microsoft.Office.Interop.Word._Application)application).Quit(ref saveChanges, ref missing, ref missing); //cast as _Application because there's ambiguity
                return text;
            }
            catch (Exception ex)
            {
                Log.error("Error converting document to text.");
                return string.Format("An error occured when converting this document to text.  The error returned is '{0}'.  \n\nYou can try copy and paste instead.", ex.Message);
            }
        }