function validate_form ( )
{
    valid = true;

    if ( document.register_form.username.value == "" )
    {
        alert ( "Please fill in the 'Username' box." );
        valid = false;
    }
    if ( document.register_form.password.value == "" )
    {
        alert ( "Please fill in the 'Password' box." );
        valid = false;
    }
    if ( document.register_form.first_name.value == "" )
    {
        alert ( "Please fill in the 'First Name' box." );
        valid = false;
    }
    if ( document.register_form.last_name.value == "" )
    {
        alert ( "Please fill in the 'Last Name' box." );
        valid = false;
    }
    if ( document.register_form.email.value == "" )
    {
        alert ( "Please fill in the 'Email' box." );
        valid = false;
    }
    var re= /^\w+([\.-]??\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/;
    
    if(re.test(document.register_form.email.value)==false)
    {
        alert("Not a valid email address");
        valid=false;
    }

    return valid;
}