Hi Samsyl,
Although what Vincent says is (as usual) correct, you could force a refresh midway through parsing a PHP document by sending a header like so:
header ("Location: ".$PHP_SELF."");
You'd use this is you were continually checking for something's existance, but it'd be MUCH better using a regular loop. If fact I can't see why you'd want to do this.
There is no real disadvantage to using the HTTP-EQUIV or JavaScript methods as described above, apart from in the situation where JavaScript might be disabled.
Regards,
David Grant