Are you talking desktop or Server?
If desktop, it'd be better to just save a backup with a date stamp each time
you save the file. After clicking on Save As, pick the options at the bottom,
and enable the save backup feature. This will save a .bak version of the
file each time you save it as an MPP. Change the name of the .bak file on
each save to add a date stamp.
If you're using Server, that can be configured in the Administrative Backup
option.
- Andrew Lavinsky
Blog:
http://blogs.catapultsystems.com/epm