I'm going to patch our NW6.5 (single) SP2 server to SP3. I know you can
tell the upgrade to create backup files (I think to c:\nwserver\backupsp3 &
sys:system\backupsp3 folders).

Is it possible to 'downgrade' SP3 back to SP2? I've looked for instructions
to do so but have not found any.

Is there an easy way to do this?