function checkform ( form )
{ 
  if (form.first_name.value == "") {
    alert( "Please enter your first name." );
    form.first_name.focus();
    return false ;
  }

  if (form.last_name.value == "") {
    alert( "Please enter your last name." );
    form.last_name.focus();
    return false ;
  }

   if (form.email.value == "") {
    alert( "Please enter your email address." );
    form.email.focus();
    return false ;
  }

   var reg = /^([A-Za-z0-9_\-\.])+\@([A-Za-z0-9_\-\.])+\.([A-Za-z]{2,4})$/;
   var address = form.email.value;
   if(reg.test(address) == false){
      alert("Please enter a valid email address");
      form.email.focus();
      return false;
   }


   if (form.phone.value == "") {
    alert( "Please enter your phone number." );
    form.phone.focus();
    return false ;
  }

   var phonenumber = form.phone.value;

if((phonenumber.match(/^[ ]*[(]{0,1}[ ]*[0-9]{3,3}[ ]*[)]{0,1}[-]{0,1}[ ]*[0-9]{3,3}[ ]*[-]{0,1}[ ]*[0-9]{4,4}[ ]*$/) == null)
 && ((phonenumber.match(/^[ ]*[0-9]{3,3}[ ]*[-]{0,1}[ ]*[0-9]{4,4}[ ]*$/)==null)))
{
 alert("Invalid phone number, please enter in the following format ###-###-####.");
 return false; 
}


   if (form.company.value == "") {
    alert( "Please enter the name of your company." );
    form.company.focus();
    return false ;
  }

   if (form.city.value == "") {
    alert( "Please enter your city." );
    form.city.focus();
    return false ;
  }

   if (form.state.value == "") {
    alert( "Please enter your state." );
    form.state.focus();
    return false ;
  }

  return true ;
}