Thanks! Actually there's a little overlap in the right part of the picture at the wall from the tower I was standing on due to wide angle perspective changes.
If you're looking for a simple stitching tool - have a look at AutoStitch with which I've done most of my recent stitches. It's very good at sorting the pictures on it's own. The only problem is that apart from the total automatic mode it doesn't offer a real manual correction mode.