Documentation - No investment in technology can compensate for proper documentation when the time comes to restore your system.  A well written plan that outlines exactly how to bring you back to full system availability is invaluable.

Adequate security - Taking all reasonable steps to prevent your system from being successfully attacked can prevent a disaster from occurring.  Properly configured Firewalls can prevent numerous methods of attack.

Anti-Virus software - Virus are used to deliver malicious programs to systems on your network.

All major providers of Enterprise Backup solutions offer disaster recovery modules.  Proper configuration and update of these programs can be the difference between a few hours of downtime and a few days.