Why configure crontab? My system automatically updates the time when I log in to the internet. The ntpdate client listens to the network time servers by itself.
I don't use windoze, so I would not be interested in its registry codes.
Okay, this is one thing that we have got to look into in Knoppix.
But that the BIOS is updated by ntpdate is absolutely confirmed. In doze, if you change time the BIOS time is affected too.