Thank you, This was VERY helpful. What all of the "how-to" threads neglect to mention is that when you go to
http://code.google.com/p/epubcheck/downloads/list you need to download the SOURCE *and* BINARY .zip files.
Most, if not all, only instruct to "download epubcheck-1.2.zip" which, well, was not terribly elaborate enough of a, ahem, command. I hope others find this thread helpful!