If you installed Outlook 2007 on a Windows Vista machine and the passwords are not saved type the following in the Start Menu, Run command or in the Start Search field of the Start menu
shell:dpapiKeys
Rename the key (it begins with S-1-5-21) and restart Outlook. Warning: 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.)
If you’re interest in more shell shortcuts take a look at http://www.itexperience.net/2008/03/02/vista-shell-commands/
If you have Windows XP and passwords are not saved, see http://support.microsoft.com/?kbid=290684.