In house data backup procedures

All,
Do you have best practices concerning backing up the Customers Data. I am looking for processes or best practices that surround the Desktop area. These would include processes to back up the users systems locally, their share drive information, and archive requests to keep the Businesses units DASDI usage down to a controllable level and to purge old files not in use daily. For all of this I am looking for best practices. How mant time you allow the user to make a request to b/u their system before thier cost center incurrs a cost.
RVAUGHAN@HELLERFIN.COM