You can't change the name of the default Contacts folders in a mailbox, but
you can make additonal contacts folders with whatever name you please.

You may need to repeat the steps below for each address book, step 2 providing the opportunity to change the display name. You will need to be able to create -- at least temporarily -- an Outlook profile that opens another user's mailbox as the primary mailbox. Proceed with these steps while logged in under your own Windows account, not the other user's:

1. Create an Outlook profile that connects directly to the other user's mailbox, not your own, and start Outlook with that profile.

2. On the Properties dialog for the other user's Contacts folder, make sure that it's set to display in the Outlook Address Book and give it a display name other than contacts, such as Joe's Contacts.

3. Close Outlook.

4. In Control Panel | Mail, edit the *same profile* (i.e. the one from Step 1) to change the mailbox from the other user's to your own.

5. Still working with the same profile, on the Advanced tab of the Exchange Server service, add the other user's mailbox as a secondary mailbox.

6. Restart Outlook, and you should see the Joe's Contacts in your Outlook Address Book as well as your own Contacts folder.