Hot off the press this month, two new must have add-ons for Outlook:
Microsoft Office Outlook Connector 12.1 Beta (with added ooomph!)
With Microsoft Office Outlook Connector, you can use Microsoft Office Outlook 2003 or Microsoft Office Outlook 2007 to access and manage your Microsoft Windows Live Hotmail or Microsoft Office Live Mail accounts, including e-mail messages, contacts and calendars for free! [GET IT HERE]
Outlook 2007/2003/2002 Add-in: Personal Folders Backup (updated version)
The Personal Folders Backup download creates backup copies of your .PST files at regular intervals, in Outlook 2002 and later versions, making it easy to keep all of your Outlook folders safely backed up. [GET IT HERE]
For instructions on how to use the .PST backup tool see this page