From the instructions in the link below, you should not be trying to open it with WinZip at all...

http://forum.nitdroid.com/index.php?topic=241.0

When you click on the down load link, windows should give you a pop-up asking you what would you like to do with this file... “open with... or save to location”? Just click on the save radio button and you are done. No need to open the file with winzip.