You must have done more than just upgrade your OS.
Add the Outlook Address Book to your Outlook Profile. We can't tell you how.
You didn't post your Outlook version.

Signature
Russ Valentine
[MVP-Outlook]
> My Contacts folder doesn't appear in the Address Book,
> and the Show this folder in the Address Book check box is
> unavailable. This happened after upgrading from Windows
> 93 SE to Windows XP. How can I get access to the
> contacts while using the address book?