BOO.
My "real AppleID (the one with hundreds of songs and hundreds of apps associated with it) is from the PRE @me.com days. I later signed up for @me.com
When the cloud started I had to choose: keep my @me address or keep all my stuff. I chose: keep hundreds of dollars worth of stuff.
What that means then, is 5GB of storage instead of 25GB (til june). BOO apple! BOO!
I had 3 apple id's. One for iTunes, one for .mac/mobileme and one for the developer program. When iCloud came along, I waited and watched. I saw the problems people were having and decided I could wait this thing out. Finally when I had all my devices up to the latest patch of the latest OS, I got an Apple genius in a chat window and visited me.com/move. It wasn't smooth. I had created a "temp" apple id just to test iCloud and when he talked me into logging out of that temp id on my mac, it deleted my calendar and contacts. Bummer. Actually it offered me a choice. I could delete everything (which I thought would do nothing since none of the data had been "created" under the "temp" id). Or I could say no I don't want to delete anything which would leave me logged in to the temp apple id.
It turns out my mobileme account was the master of a family pack. As the migration moved forward, I discovered I would lose the ability to administer that mobileme account. No big deal. Let the kids move their own stuff. After about 45 minutes, all my stuff came back. One of the last steps in the "move" is to make sure at least one device has "good data". My iPhone had all my contacts and they all came back on my Mac when I logged in to the "moved" mobileme id. Note that I did NOT associate my apple id with the iTunes ID I used to buy music and apps. I know this is "recommended" but I refused. I still have 3 "apple ids", one for iCloud, one for iTunes and a separate developer ID. And that's the way I like it.
So. Have you closed your old mobile me account? If not, you can go in iTunes and associate a new email address with your iTunes account. I cannot caution you strongly enough that associating a me.com email with your iTunes purchases is a risky venture at this time of transition! Once you've done that, back up your contacts, calendar and any photos in your photostream and any documents you may have in icloud. Export them as regular files and put them someplace safe.
You can now go "sign out" of the icloud id you created that left you with only 5 gig of storage. It WILL delete all your stuff. In your case it will delete it not only on your Mac but on your iThings as well. Don't panic. You can then go to me.com/move and migrate your mobileme account to iCloud. It should bring over any contacts you have still sitting in mobileme but if it doesn't that's why you exported from address book, ical, etc a few steps back. Finally after your new icloud account is up and running from your "moved" mobileme account, you can go to your backups and import anything that got "deleted" during the process where you discarded the 5 GB mobile me account.
An alternative to all this pain is to call AppleCare and explain your situation and see if they will bump your storage since you had a mobile me account that for whatever reason you decided not to simply upgrade to iCloud.
So far, two of our 4 mobile me accounts are moved to iCloud and I love the way photos simply show up in iPhoto. I just have to remember to go in and add them to events before they get deleted after 30 days. Maybe I'll write an Applescript to do this so I don't have to remember all the time.
hope this helps...
