It looks like your note was printed in Sept of 2007 and they printed 9.6million star notes. A higher printing, but not a bad find. I can't really tell the condition...but this seems to be a more common star note, so I probably wouldn't keep it because it's $20...but if you can afford it, no reason to spend it.
it looks like the note has some creases and folds, but it is tough to tell for sure. As Richie said, i would keep it if you can afford it
as we can tell I have not updated my camera over the summer. It only has the middle wallett fold. I probably will keep it. If it was a fifty or a hundred I wouldn't. besides mabye the other 9.599999 mil will get ruined in a thousand or so years!!!!