maestro!!!
quedó asi:
Código:
<!--[if (gte IE 7) | !(IE)]>-->
<script type="text/javascript">
if (screen.width<1024)
document.write ('<link rel="stylesheet" type="text/css" href="800px.css"/>')
else
if (screen.width>1024)
document.write ('<link rel="stylesheet" type="text/css" href="1000px.css"/>')
else
document.write ('<link rel="stylesheet" type="text/css" href="1000px.css"/>')
</script>
<!--<![endif]-->
<!--[if lt IE 7]>
<script type="text/javascript">
if (screen.width<1024)
document.write ('<link rel="stylesheet" type="text/css" href="800pxie6.css"/>')
else
if (screen.width>1024)
document.write ('<link rel="stylesheet" type="text/css" href="1000pxie6.css"/>')
else
document.write ('<link rel="stylesheet" type="text/css" href="1000pxie6.css"/>')
</script>
<![endif]-->
Trabaja al 100%, muchas gracias!!