Bob wrote:

how do you disable the use of PSTs?

Google Groups is your friend.
http://groups.google.com/groups/search?q=group%3Amicrosoft.public.outlook.*+%2Bdis able+%2Bpst+%2B%28policy+OR+registry%29&qt_s=Searc h+Groups
--
Brian Tillman [MVP-Outlook]