Recently I ran into an issue where dynamically loaded CSS files were not being executed/rendered in IE6-8. The loading of that file happened with a line in jQuery code using appendTo. With jQuery 1.4 however this stopped working and so far to my knowledge this has not been fixed.

A work-around would be to just revert to plain good old fashioned javascript like the code below

<script>
var headID = document.getElementsByTagName("head")[0];
var cssNode = document.createElement('link');
cssNode.type = 'text/css';
cssNode.rel = 'stylesheet';
cssNode.href = 'presentation/css/js-enabled.css';
cssNode.media = 'screen';
headID.appendChild(cssNode);
</script>