function checkEmail(theEmail) {
	var filter  = /^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/;
	return filter.test(theEmail);
}
function validate_form ( ) {
    valid = true;
	
    if ( document.theForm.email.value == "" )
    {
        alert ( "Please enter your email address." );
        valid = false;
    } else if (!checkEmail(document.theForm.email.value) )
    {
        alert ( "Please enter a valid email address." );
        valid = false;
    } else if ( document.theForm.name.value == "" )
    {
        alert ( "Please enter your name." );
        valid = false;
    } else if ( document.theForm.comments.value == "" )
    {
        alert ( "Please enter your comments." );
        valid = false;
    } 
    return valid;
}