I have a client that is currently running Exchange 5.5 and doing monthly
backups retaining them for 7-years. They have plans to migrate up to
Exchange2003. That's not a problem going forward, but what about all the
monthly data in Exchange 5.5 format....can I restore a 5.5 database into a
2003 server? Or would they need to keep an 5.5 server around just to restore
these monthly backups?

This goes along with the threads on this list about long-term retention of
data and being able to recover that in the future.

Bill Boyer
"An Optimist is just a pessimist with no job experience."  - Scott Adams