For Outlook 2007 customers this doesn’t need to be applied. For 2003 customers(with sp2 or 3) who refuse to use outlook 2007 for whatever reason, but have their mailbox homed on Exchange 2007, you can apply this registry setting to force Outlook to use online Global Address List when they use Cached Exchange Mode:
Outlook 2003
HKEY_Current_userSoftwareMicrosoftOffice11.0OutlookCached Mode
Parameter: DownloadOAB
Type:REG_DWORD
Value: 0
Close outlook and restart Outlook.
THis has been tested and it works great
Ex-Shell 