function CheckForm() { 
 var name = contact_form.name.value;
 if (name == "") { 
    alert("Please enter your name."); 
    contact_form.name.focus();
    return false; 
}
 if (contact_form.email.value.indexOf ('@',0) == -1 ||contact_form.email.value.indexOf ('.',0) == -1){
    alert ("The email address you entered is not valid. Please re-enter your email address.")
    contact_form.email.focus();
    valid = false; 
    return false ;
}
 var name = contact_form.comments.value;
 if (name == "") { 
    alert("You have not entered any comments."); 
    contact_form.comments.focus();
    return false; 
}
 return true; 
}