Outlook Address Lists
Change The Default Address List When Sending E-mail Messages - (The "To:" Button) in Outlook 2002
From the Outlook Toolbar:
Click on the Address Book icon
From its "Tools" Menu, select "Options"
The Addressing page will be displayed. The first item on that page is "Show this address list first"
Click the drop-down arrow next to it on the right
Scroll through the selections to locate your preferred choice (Global Address List, Contacts, etc) and select your preferred choice
Click "OK" to exit the screen and save your choice
Close the Address Book.