function checkForm() {
  bIsValid = false;
  sError = "";

  if (document.contact.txtName.value == "") 
    sError += "Please enter your name \n";
     
  if (document.contact.txtEmail.value == "") 
    sError += "Please enter your E-Mail Address\n";  
  else if (document.contact.txtEmail.value.indexOf('@',0) == -1 || document.contact.txtEmail.value.indexOf('.',0) == -1)    
      sError += "Your E-Mail address is not correct\n";     
   
  if (document.contact.txtMessage.value == "") 
    sError += "Please enter your message\n";   
  
  if (document.contact.captcha_code.value == "") 
    sError += "Please enter Antispam code.\n";             

  if (sError == "")  
    bIsValid = true;
  else
    alert(sError);
  
  return bIsValid;  

}