a couple of problems with PHP form

I am trying to set up some validation for my php form with the email field using the following code: if(!eregi("^(.+)@(.+)\\.(.+)$",$_POST['email'])) { $error_msg .= "<BR />Your email appears to be invalid."; $ok = "false"; } I am trying to accomplish not being able to enter anything other than a valid email string ....this doesn'r seem to be doing anything. also, I want the field to appear hilighted when there is no information so I am doing this: <input class="<? if($error_msg){ echo "error"; } ELSE { echo "normal"; } id="firstname" name="firstname" type="text" value="{$_POST['firstname']}"? />" and I have an error class set up in my CSS, such as .error {border: 1px solid red;} this is not doinf anything either. Can somone point out what may be wrong with this PHP code? thanks,