Show Global address book in Outlook Contacts?

It will come by default if you have configured your account to Exchange.
If you are configured your Outlook to POP3 or IMAP then you need to add LDAP address book.
Let me know if you are using POP3? I can provide the procedure to add LDAP address book.

No im using exchange.  I can see the address book if i press tools from the menu bar and then address book but i want it to show when i click contacts. Can this be done?

No that is not possible, you can save or Add any contacts from Global Address book to the Local Contact if you want to achieve this.
But why do want to that anyway?

The address list also contains each of our users ext so i want people to be able find search for extensions through contacts.

They will be able to find from Global Address list..what is the need to find it from Contacts?

Search for the person name and then lookup the ext.  The ext is stored under business phone number within the global address list.  

I'm just setting up Exchange and Outlook and still working from a test system.  At the moment all names, telephone numbers are typed on word and email around - people often move and the printed word documents contains out-dated information.  I know from working at other companies there are better ways of displaying this information.  We have all the details within Active Directory and I thought Outlook would be a good way to display the contact information and it would be searchable.

im open to ideas, how is internal contact info displayed within your business?

It is through GAL and I have suggested is the best way to achieve that.

Thanks alot for your help :-)