iPod keeps synching

After synching the contacts and calendars once with my new classic 80 G I have "told" iTunes, that it should not synch contacts and calendars any more, because there are not so many changes, that I need the constant time consuming synching. But iTunes does not listen, it keeps synching every time the iPod is hooked to the iBook....And then I cannot choose the calendars I want to sync, if I choose some, it synchs all of them.