IE 6 and GZIP

hi,
I was trying to check if IE browser supports GZIP compression programmatically. I think IE 4 + supports GZIP compression but when I displayed the header and checked using response.getHeader(), it gave: null. Not sure whats happenning. Please give me a clue....
Please see my code below.
When I access my servlet from IE 6+, "encoding" String value is null and so I get the message that compression is not supported.

With Netscape 4.79 it says it supports GZIP compression and "encoding" String value is "gzip" and the message is correct.
IE 6+ supports GZIP compression, isn't it? What's wrong with the code?

import java.io.IOException;
import java.io.PrintWriter;
import java.util.zip.GZIPOutputStream;
import javax.servlet.ServletConfig;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
 
public class TryGZip extends HttpServlet {
 public void init(ServletConfig config) throws ServletException {
 super.init(config);
 
 }
 
 public void doGet(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
 
 // Get the "Accepting-Encoding" header from the HTTP request.
 String encoding = request.getHeader("Accept-Encoding"); 
 boolean supportsGzip =false;
 System.out.println("encoding: "+encoding); 
 if (encoding != null) {
 if (encoding.toLowerCase().indexOf("gzip") > -1) 
 supportsGzip = true;
 System.out.println("Yes! browser SUPPORTS gzip"); 
 } else
 System.out.println("No! browser DOES NOT support gzip!!"); 
 
 if (supportsGzip == true) {
 System.out.println("supportsGzip== true");
 // Set the response header.
 response.setHeader("Content-Encoding", "gzip");
 response.setHeader("Content-Type", "text/html");
 
 try {
 StringBuffer sb = new StringBuffer();
 sb.append("<html>");
 sb.append("<head><title>GZippedServlet</title></head>");
 sb.append("<body>");
 sb.append("The servlet has received a POST. This is the reply. ");
 sb.append("This browser SUPPORTS GZIP!!!</body></html>");
 GZIPOutputStream gzos = 
 new GZIPOutputStream(response.getOutputStream());
 gzos.write(sb.toString().getBytes());
 gzos.close();
 } catch(IOException ie) {
 // handle exceptions
 
 }
 } else {
 System.out.println("supportsGzip == false");
 // GZIP is not supported by the browser.
 
 PrintWriter out = response.getWriter();
 out.println("<html>");
 out.println("<head><title>GZippedServlet</title></head>");
 out.println("<body>");
 out.println("The servlet has received a POST. This is the reply. ");
 out.println("This browser DOES NOT SUPPORT GZIP!!!</body></html>");
 out.close();
 
 } 
 
 } 
}

Thanks for the help.
-raj