You'll need to install Google Apps Sync, a plug-in for Outlook 2003, 2007, or 2010, if you want to use Outlook to manage your Google Apps mail, calendar, and contacts—along with your Outlook notes, tasks, and journal entries.
Google Apps Sync synchronizes mail, calendar events, contacts, and notes between your Google account in Outlook and your Google Apps account on the web, so you can access the same information at any time from either interface.
This enables you to manage your GMail and Google Calendar using the familiar Outlook interface and continue to benefit from Outlook capabilities like mail merge that are not currently available for GMail.
Google Apps incorporates several useful functions that Outlook does not, including online chat and the ability to retract a message if you hit Send by mistake. Also, because it's on the web and not on your local computer, it's one less program to troubleshoot if something goes wrong.
If you do decide to move from the Outlook interface to the Google Apps interface, Google offers a wealth of tips on their website.
To install Google Apps Sync:
Note that you need administrative privileges on your computer to complete the installation. If you don't have these, contact your ITC for assistance.