Juice doesn't work on Vista because of a bug in Python. On on Windows XP python reports 'Windows' for platform.system(), but on Vista platform.system() returns 'Microsoft'. This has been submited to python as a bug (http://sourceforge.net/tracker/index.php?func=detail&aid=1726668&group_id=5470&atid=105470).
This patch changes to using 'win32' == sys.platform to find out if the platform is windows.
This patch is against the trunk.