JavaScript - Redirect for MAC

[meztec]

Here's what im trying to do:
Redirect a user if their using MAC IE 4 or below.

Here's my code:
<!--IE/Mac redirect-->
<script language="JavaScript">
{
if(navigator.userAgent.indexOf('Mac') != -1 && navigator.appName.indexOf('Microsoft') !=-1 && navigator.appVersion.indexOf('4.')>=0)
{ window.location.href="index.html"; }
}
</script>
<!--end script-->

--It works but it also redirects IE 5 users.
Any advice or things I should fix with this code.
Thanks

[Arielladog]

Try using this:

if(navigator.userAgent.indexOf('Mac') != -1 && navigator.appName.indexOf('Microsoft') !=-1 && navigator.appVersion.indexOf('4.')>=0 && !document.getElementById){

aDog