For email, contacts and calendars, Google’s services offer features that closely parallel what MobileMe has – and they won’t cost you a penny. You can sync your data between multiple computers and Google’s cloud of servers; you can access your data in any web browser; and you can choose over-the-air push synchronisation for mobile devices. For other types of data (to-do items, notes and bookmarks), the syncing story is much different, but with some effort, you can achieve much of what MobileMe offers at a fraction of the price.

Be aware, though, that differences between how Google stores data and the ways Apple’s Address Book and iCal do, mean some items, such as Address Book groups, don’t sync at all.

Basic setup: Before you begin, back up all the contact and calendar data on your Mac, as discussed earlier. If you’re using Google Apps (for a custom domain name), also make sure you’ve enabled Google Sync for your domain by following Google’s instructions (www.macworld.com/6846). And, if you use an iOS device, be sure to sync it with your Mac.

Email: If you use a browser for email, then syncing is a non-issue. However, if you prefer to use a conventional email client such as Mail in OS X or iOS, you can set it up to access your Gmail account. Gmail lets you connect by using POP, IMAP or Exchange ActiveSync, but only the latter two automatically keep all your email in sync across devices.

To sync iCal with Google Calendar, enter your Gmail credentials and then follow the prompts

Before you can access your Gmail account from Mail, you must turn on IMAP support. To do this, go to www.gmail.com (or, if you use Google Apps for a custom Gmail domain name, go to the URL you normally use) and log in. Click on the Settings link and click Forwarding And POP/IMAP. Then, in the IMAP Access section, select the Enable IMAP checkbox. Save it by clicking on Save Changes.

Next, in OS X’s Mail, choose Mail > Preferences, click Accounts and click the button marked +. Enter your full name, your Gmail address (for Google Apps users, include the @ sign and the domain name), and your password, and then click Create. Mail automatically configures the account to use IMAP.

On an iOS 4 device, the easiest way to configure Gmail to use IMAP is to tap Settings  > Mail, Contacts, Calendars > Add Account > Gmail, enter your credentials, tap Next and then, after your credentials are verified, simply tap Done.

However, you can also use Exchange ActiveSync to access your Gmail account on your iOS device. This gives you the option of push email and automatically syncs your Google calendars and contacts without any further hassles. The instructions for setting up your iOS device to access Gmail using Exchange Active-Sync are somewhat lengthy, but Google spells out all the details on its website (www.macworld.com/6847).

Contacts in OS X: To sync Address Book with Gmail Contacts’ My Contacts list, open Address Book, choose Address Book > Preferences, click Accounts, select On My Mac in the Accounts list on the left and then click the Account Information tab. Select the Synchronise With Google checkbox, and then click Configure. If you’re setting up Google syncing for the first time, an alert appears explaining about the synchronisation process; read this and click Agree. Then, in the dialog box that appears, enter your Gmail address in the Google Account field and your password in the Password field, and click OK. You may see a warning that Address Book can’t verify the identity of the server; if so, click Continue.

Next, make sure the Sync menu appears in your Mac’s menu bar, as discussed earlier. Choose Sync Now from the Sync menu. During the initial sync, if the Conflict Resolver window appears, click Review Now, decide which version of each contact to use, and then click Sync Now. After the first sync, OS X should sync changes once per hour, although you can use the Sync Now command at any time to sync manually.

Calendars in OS X: To sync iCal with Google Calendar, open iCal, choose iCal > Preferences, click on Accounts, and click the plus-sign (+) button. Choose Google from the Account Type pop-up menu, and enter your full email address (whether ending in @gmail.com or your custom domain) in the Email Address field and your password in the Password field, and click on Create. You may see a warning that iCal can’t verify the identity of the server; if so, click Continue. Your primary Google calendar then appears in iCal. To sync additional Google calendars, click the Delegation tab in the Preferences window and select the Show checkbox for one or more calendars.

This procedure syncs existing Google calendars with iCal, but not the other way around. To move your existing iCal data into Google Calendar, find one of your calendars in Google on the left side of the screen, click the Settings button beneath it, click Import Calendar next to the Create New Calendar button and then, in the dialog box that appears, click Browse.

Navigate to the iCal backup file you created earlier, and select it. In the Import Calendar dialog box, select the calendar to which you’d like to add the events (if you have more than one) from the Calendar pop-up menu and then click the Import button to bring your calendar info in.

By default, iCal syncs with Google Calendar every 15 minutes (or when you add, delete, or change an event on your Mac), but you can change the interval, if you like, by clicking on the Account Information tab in the Preferences window and choosing a new value from the Refresh Calendars pop-up menu.

When you’re finished configuring a Gmail account on your iOS device to use Exchange ActiveSync, the screen should look something like this

Calendars and Contacts in iOS: To sync contacts and calendars on your iOS device, go to Settings > Mail, Contacts, Calendars and tap Add Account at the bottom of the Accounts list. Tap Microsoft Exchange, enter the full email address associated with your Google account in the Username field and your password in the Password field; leave the Domain field blank. Tap Next. If an Unable To Verify Certificate message appears, tap Accept. In the Server field, enter m.google.com, and tap Next again. Make sure Contacts and Calendars are turned on (plus Mail, if you want to sync your Gmail email using Exchange ActiveSync) and tap Done. When prompted to choose a way to handle existing data, tap Delete. Synchronisation begins momentarily and then everything happens wirelessly.

Bookmarks: Google can sync bookmarks from its Chrome browser between computers, and can provide an editable list of bookmarks (at www.google.com/bookmarks) that you can access within any browser window. However, unlike MobileMe, Google doesn’t offer an option for syncing Safari’s built-in bookmark list (either the desktop or iOS version).

Instead, you can use a service such as LastPass’s Xmarks (www.xmarks.com), which lets you synchronise bookmarks across browsers, devices and platforms. It supports Safari 4 and 5 on Leopard and Snow Leopard, as well as Firefox 3 and the beta of Firefox 4. Basic service is free, and the $12 (£7) per year Premium version adds iOS support and more.