cannot upgrade from quicken 6 to quicken 8

I have been unwilling so far to use the upgrade disk I bought several years ago .. However I upgraded my computer and felt to upgrade to 8 as I payed for the disk. when attempting to upgrade I recieve the error message "no registered version of quick books found" and the upgrade fails does anyone have the answer as I have found no relevant post on this forum .. or on the web.. I have a 2k laptop and my new machine is xp and I have had the same result on both thanks John