From http://www.slipstick.com/outlook/usertips.htm:
To make Outlook 2002 go to the Windows system tray when you minimize it edit this key:
HKEY_CURRENT_USER\\Software\\Microsoft\\Office\\10.0\\Outlook\\Preferences
Add a new DWORD value named "MinToTray" and give it a value of 1.
To clear the Find a Contact list delete this key:
HKEY_CURRENT_USER\\Software\\Microsoft\\Office\\9.0
\\Outlook\\Contact\\QuickFindMRU
You can also modify the QuickFindMRU value to a zero-length binary value.