Outlook 2007 is nice enough to put all of its accounts into a single
HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows Messaging Subsystem\Profiles\
Just export that key and import on a new machine and you will get all your accounts. Note that if you are using IMAP you don’t even have to backup your email data. I use
IMAP via Google and all the emails I ever need are safe.