2002-2000 "Downgrade" - where are the preferences stored?

I have downgraded back to Outlook 2000 but cannot now send
or receive email. The accounts and personal folders are
all still there. Accounts work fine in Express as they did
in 2002 and in 2000 before I upgraded. Has the downgrade
left some 2002 profile/preferences on my system and if so,
where are they so that I can delete them. I'm quite happy
to start with a "vanilla" install and reset accounts etc.