How to correct Duplicating addresses and calendar?

I tried to use iCloud but with Snow Leopard it dos not work I guess I wil hv to switch to Lion and upgrade a bunch of apps

Meanwhile my address book and Calendaron my iPad and Power Book are full of duplicates well ove 2,000

I need a script to go through my Power Book and iPad to get rid of them - and guidance on how to prevent sch future fiascos

Meanwhil I have deleted what I can about iCloud - if that was the culprit