Thanks for the head's up. I was so giddy with the simplicity of the solution, I stopped trying to poke holes in it.
I agree with your philosophy of not "reinventing the wheel", but I did notice two things: First, the link you provided claims in the features section that rsync if for *nix systems, so I am assuming I'll need a port of it for windows systems; however looking at a Python rsync module I found, it looks like it's just doing file-copy (which I have already solved). So I'm wondering if you know off-hand which windows port does this checksum validation you outlined. -- http://mail.python.org/mailman/listinfo/python-list