Using a server cluster helps to create a fault-tolerant environment by linking multiple servers together to function as a single system. If one server fails, the others in the cluster can take over, thereby preventing a service outage. A workstation cluster is not a common or practical solution as workstations aren't designed for server tasks. Rebooting a single server regularly only introduces downtime and doesn't prevent failures. Antivirus software protects against malware but doesn't address hardware failures. UPS devices protect against power issues but wouldn't take over the tasks of a failed server. Disabling unused services improves security but does not contribute to fault tolerance in terms of hardware failure.