CODE
if(navigator.userAgent.indexOf('MSIE') != -1)
{
var style = document.getElementsByTagName('head')[0].appendChild(document.createElement('link'));
style.rel = "stylesheet";
style.type = "text/css";
style.href = "msie.css";
}
Just an example of a stylesheet that would only load in MSIE. You can use document.all, etc. checks instead for wider support.