If you installed Outlook 2007 on Vista and are having problems with the password not getting saved, type (or paste)

shell:dpapiKeys

in either Start Menu, Run command or in the Start Search field of the Start menu. Rename the key (it begins with S-1-5-21) and restart Outlook. You’ll lose any passwords that might be there. (Passwords are stored in hidden system files in this folder, so while the folder looks empty, its not.)

Other shell shortcuts are listed at http://www.poremsky.com/p/vistashortcuts.htm. One of my favorites is
shell:Local AppData
This opens the hidden C:\Users\username\AppData\Local folder; *.pst are stored in Microsoft\Outlook under this path. It also shows the hidden C:\Users\username\AppData\Roaming folder in the folder tree. Other Outlook support files are under the Microsoft\Outlook folder in this path.  (shell:AppData goes direct to Roaming folder.)
 
If you’re using Windows XP and passwords won’t save, see http://support.microsoft.com/?kbid=290684.