You know, there may be an easier way to do this.
Since that *IS* HTML, don't even try to treat it as XML.
Instead, put a HIDDEN <iframe> on your page and load the HTML in that <iframe>.
Then you can just use HTML DOM methods in your JS code to grab the relevant data out of the <iframe>!
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.