I found this at Dynamic Drive a while ago, I hope it helps, I love that site.
ASlater
Auto Maximize window
In the head section:
<script language="JavaScript1.2">
<!--
/*
Auto Maximize Window Script- By Nick Lowe (
[email protected])
For full source code, 100's more free DHTML scripts, and Terms Of Use
Visit
http://www.dynamicdrive.com*/
top.window.moveTo(0,0);
if (document.all) {
top.window.resizeTo(screen.availWidth,screen.availHeight);
}
else if (document.layers||document.getElementById) {
if (top.window.outerHeight<screen.availHeight||top.window.outerWidth<screen.availWidth){
top.window.outerHeight = screen.availHeight;
top.window.outerWidth = screen.availWidth;
}
}
//-->
</script>