Hey I had the same problem, spent a long time trying to figure out where I went wrong, in the end I found nothing except a different GUI for xdelta. Somehow this one worked when the other didn't, couldn't find the original link so I chucked it on
mediafire. File contains xdelta, the GUI posted here and the one I found, good luck.
http://www.mediafire.com/?7as3kiw780p2g05