How do I turn off iCloud on my iPhone & iPad without losing data?

I've been a staunch Apple user since my old Apple IIGS. I'm running the latest Snow leopard, and had already made the decision NOT to upgrade to Lion when I found out that Quicken wouldn't work. I don't use MobileMe, and manually synched my "new" iPhone 4 and 1st geiPad thru iTunes. When I upgraded my iPhone to IOS 5, I had problems with my music that I FINALLY was able to straighten out. I then set up an iCloud account, as it promised to be a better way to keep everything on my 3 devices synchronized. When I synched with my computer, my iPhone & iPad both got double events in iCal. I've figured out that the events were loading from the computer AND from the cloud. I've been reading discussion groups that say that once you've set up iCloud, if you turn it off (or delete the account) you'll lose all the data on your computer that you've sent to the cloud (which in my case is Contacts & iCal).

What I really need is good advice on how to reset my devices to "pre iCloud" without losing any data. I hope someone can help me. I usually am somewhat slow in jumping on the "newest technology" bandwagon. Thanks!