Since you're already using jQuery, just go the whole hog and use the jQuery DOM methods to do this. Any performance hit has already been taken by loading jQuery in the first place.

You would want either prepend() or prependTo(). $.browser is deprecated, so you shouldn't be using it; and in this instance you don't actually need it. jQuery methods should handle all the cross-browser bugs internally.

Example:
http://jsfiddle.net/tr333/Pk78H/1/