To archive your old Exchange account messages, you could create a rule
(Exchange) that moves e-mail messages:
1. Create a new Exchange Rule (Tools > Rules) titled "Archive"
2. Set the criteria to "Date Received is greater than XX days old" where XX
is some number of days you wish to archive beyond
3. Set the action to Move the message to another Entourage folder that is
under Folders on My Computer (You may want to create a whole series of
Archive target folders)
4. I'd recommend not enabling the rule to run each time a message comes in
5. Go to each Exchange folder, select all messages
6. Menu: Messages > Apply Rules > Archive
This will go through all the selected messages and move the older messages
for you. Of course, you have to do this with each folder on your Exchange
account and ideally you'd have separate rules for each folder.
If you want to move everything and empty your Exchange account, you can
create the same rule using "All messages" as the criteria.
-Andy