doing a defrag and scandisk should not cause any issue, but to be safe, it should be done during non production hours. Defrag with Windows 2000 sometimes can cause high CPU utilization as well.
Though, installing and running Norton Ghost is not supported nor recommended with CallManager. If you are trying to build a Lab server identical to your Production system, you should install a fresh version of CM and restore data using BARS. For information about how to use BARS you can refer:
http://www.cisco.com/en/US/customer/products/sw/voicesw/ps556/prod_maintenance_guides_list.html
Hope this helps
