Detect the browser using ASP.NET and C#

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;

public partial class Default2 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        bool i=supportedBrowser();
        Response.Write(i);
    }

    public bool supportedBrowser()
    {
        string HTTPUserAgent = string.Empty;
        string BrowserName = string.Empty;
        bool isSupportedBrowser;
        HTTPUserAgent = Request.ServerVariables["HTTP_USER_AGENT"];
        BrowserName = BrowserType(HTTPUserAgent);

        if (BrowserName == "Microsoft IE 9" || BrowserName == "Microsoft IE 8" || BrowserName == "Microsoft IE 7" || BrowserName == "Microsoft IE 6")
            isSupportedBrowser = true;
        else
            isSupportedBrowser = false;
        return isSupportedBrowser;
    }

    public string BrowserType(string strHTTPUserAgent)
    {
        string strBrowserUserType = string.Empty; //Holds the users browser type
        //Get the uesrs web browser NOTE: DO NOT CHANGE THE ORDER OF WHAT IS SEARCHED!!
        //Internet Explorer
        if (strHTTPUserAgent.Contains("MSIE 9"))
            strBrowserUserType = "Microsoft IE 9";
        else if (strHTTPUserAgent.Contains("MSIE 8"))
            strBrowserUserType = "Microsoft IE 8";
        else if (strHTTPUserAgent.Contains("MSIE 7"))
            strBrowserUserType = "Microsoft IE 7";
        else if (strHTTPUserAgent.Contains("MSIE 6"))
            strBrowserUserType = "Microsoft IE 6";
        else if (strHTTPUserAgent.Contains("MSIE 5"))
            strBrowserUserType = "Microsoft IE 5";
        else if (strHTTPUserAgent.Contains("MSIE 4"))
            strBrowserUserType = "Microsoft IE 4";
        else if (strHTTPUserAgent.Contains("MSIE 3"))
            strBrowserUserType = "Microsoft IE 3";

        //Firefox
        else if (strHTTPUserAgent.Contains("Firefox/2"))
            strBrowserUserType = "Firefox 2";
        else if (strHTTPUserAgent.Contains("Firefox/1"))
            strBrowserUserType = "Firefox 1";
        else if (strHTTPUserAgent.Contains("Firefox"))
            strBrowserUserType = "Firefox";

        //Netscape and Mozilla
        else if (strHTTPUserAgent.Contains("Netscape/8"))
            strBrowserUserType = "Netscape 8";
        else if (strHTTPUserAgent.Contains("Netscape/7.2"))
            strBrowserUserType = "Netscape 7.2";
        else if (strHTTPUserAgent.Contains("Netscape/7.1"))
            strBrowserUserType = "Netscape 7.1";
        else if (strHTTPUserAgent.Contains("Netscape/7.0"))
            strBrowserUserType = "Netscape 7.0";
        else if (strHTTPUserAgent.Contains("Netscape6"))
            strBrowserUserType = "Netscape 6";
        else if (strHTTPUserAgent.Contains("Mozilla/5"))
            if (strHTTPUserAgent.Contains("rv:1.7"))
                strBrowserUserType = "Mozilla 1.7";
            else
                strBrowserUserType = "Netscape 6";
        else if (strHTTPUserAgent.Contains("Mozilla/4"))
            strBrowserUserType = "Netscape 4";
        else if (strHTTPUserAgent.Contains("Mozilla/3"))
            strBrowserUserType = "Netscape 3";
        else if (strHTTPUserAgent.Contains("Netscape"))
            strBrowserUserType = "Netscape";
        else if (strHTTPUserAgent.Contains("Mozilla"))
            strBrowserUserType = "Mozilla";

        //Opera
        else if (strHTTPUserAgent.Contains("Opera 8"))
            strBrowserUserType = "Opera 8";
        else if (strHTTPUserAgent.Contains("Opera 7"))
            strBrowserUserType = "Opera 7";
        else if (strHTTPUserAgent.Contains("Opera 6"))
            strBrowserUserType = "Opera 6";
        else if (strHTTPUserAgent.Contains("Opera 5"))
            strBrowserUserType = "Opera 5";
        else if (strHTTPUserAgent.Contains("Opera 4"))
            strBrowserUserType = "Opera 4";
        else if (strHTTPUserAgent.Contains("Opera 3"))
            strBrowserUserType = "Opera 3";
        else if (strHTTPUserAgent.Contains("Opera"))
            strBrowserUserType = "Opera";

        //Else unknown or robot
        else
            strBrowserUserType = "Unknown: " + strBrowserUserType;

        return strBrowserUserType;
    }
}