Here’s how you can add you Gmail account to Outlook 2007.
First we need to make sure your Gmail account is set up to enable POP (Post Office Protocol). In Gmail just go to mail settings and choose the Forwarding and POP tab. Click on one of the options to enable POP.
Now open up Outlook 2007 and go to Tools -> Account Settingsâ€¦
Under Account Settings choose the E-mail tab and click on New…
Enter in all of your Gmail account information (make sure Manually configure server is not checked). You do not have to go through these extra steps. Just click on Next.
After Outlook has successfully configured the e-mail server settings you can go ahead and click Finish.
Go back to your inbox and hit send/receive and you are done!
Source: PC Tips Box