First things first: you need to make sure that you're now running Mac OS X 10.7 "Lion" on your Mac (just a sec, I'll get to the PC). This is most easily done by clicking on the Apple on the top left of your Mac then choosing "About This Mac" from the menu. You should see "10.7.x" where 'x' might be a '2', a '3', etc. As long as you're seeing 10.7.2 or newer, you're ready to start.

If you're on a PC, here's what Apple says: "For your PC to be iCloud ready, you'll need Windows Vista (Service Pack 2) or Windows 7. Outlook 2007, Outlook 2010, or an up-to-date version of your preferred browser is required for accessing your email, contacts, and calendars in iCloud." You'll also need to download the iCloud control panel for your PC. Since it's such a different process, I'll let you jump over to Apple.com for that tutorial: get started with iCloud on your PC.

If you're still here, I'll assume you have a Mac of some sort as your base device for MobileMe and want to (or, more accurately, are required to) migrate to iCloud.

Before you proceed, you need to ensure that every app on your Mac is up to date, notably including Safari. This is easily done by choosing "Software Update..." from that same Apple menu on the top left of your screen. Let it run, install any updates it suggests, restart your computer and you're ready to go!

Start by choosing "System Preferences..." from the Apple menu, then clicking on the "iCloud" system preference, one you might not have noticed before. There's a "MobileMe" preference pane too, but ignore that for now, we won't need it.

iCloud will show up and tell you that you haven't migrated yet:

Click on the "Move to iCloud" button on the bottom and it'll launch your Web browser and you'll start falling down the rabbit hole that is iCloud. No, really, it's okay. Just proceed and your next screen will be this:

Click on "Get Started" if you're ready, and presumably you are, which is why you're reading this tutorial, right?

If you aren't signed in to your MobileMe account, go back to the MobileMe preference pane and sign in, then click on the "Move to iCloud" button again on the iCloud pane so that it shows you are signed in.

That's good. I don't much care about my @me.com email address (it's pretty much just spammers who use it, as far as I can tell) but I'm definitely reliant on my shared calendar...

Click on "Next".

I don't use iDisk or iWeb, but I have a lot of private photo albums from my children's school events on MobileMe Gallery, so I'm glad to know they'll all still work for at least another ten months or so. What happens after that I don't know, but hopefully Apple will either extend it further or migrate it to some sort of iGallery service or similar, even one with a small subscription fee. I'd pay it because the tight integration with Aperture and iMovie make it very worthwhile...

Click on "Next".

Not being able to sync Dashboard Widgets, Dock Items, Keychains, Preferences, etc, don't concern me as I wasn't using those in the first place. If you were, well, you gain some things (iCloud is free) you lose some things, I suppose. There are probably workarounds for most of these changes, by the way...

Click on "Next".

This is an important step. If your iOS devices aren't running the very latest version of the iOS firmware, you'll need to upgrade them before iCloud will work properly. Ditto all your Macs and all your PCs that are connected to MobileMe and will end up using iCloud instead.

Done? Check the box adjacent to "All of the devices I want to use with iCloud are now running the required software" and click on "Next" again.

I find this a bit puzzling, actually, because one of your devices has to be up to date. The only explanation I can offer is that perhaps your computer or device that has the latest contacts and bookmarks isn't one you're going to hook up to iCloud, but that seems unlikely. Anyway, ready to proceed?

Click on "Next".

Before you go further, it's a smart idea here to make a backup of your iCal and Address Book data. Just in case.

In iCal, choose "Export..." from the "File" menu, then select 'iCal Archive". It'll save the calendar archive in your Documents folder. Useful to have anyway as an insurance policy.

In Address Book, choose "Export..." from the "File" menu too, but this time you'll want to select "Address Book Archive". It'll also be saved in your Documents folder.

Well done. Backups are good. :-)

Click on "Next".

You read these, right? I mean, every line, all the way down, all the legalese that's so scintillating. Yeah, me neither. Whatever. Check the box "I agree to the iCloud Terms of Service" (whatever they are!) and you're finally ready to migrate!

Click on "Move to iCloud".

A short amount of time passes and then you get to learn just how big your calendar and other data files are. Mine's rather full of events:

14,041 events. That's over 38 events/day for a year. Jeez, no wonder I'm tired. :-)

After much time, you'll get a pop-up window on your Mac (not in the Web browser) that indicates the system itself knows you're in the process of migrating:

Click on "OK".

A few moments later, the good news:

Congrats indeed. Now you'll find that your calendar is empty, so you'll definitely want to read my next article on how to add all those critical iCal calendar events from your iCloud calendars. Otherwise, you should be good to go!