The difficulty of a hard drive replacement varies substantially with the design of the computer in question. Some computer cases are designed for quick hard drive replacements that sometimes can be done without shutting the computer down, while performing replacements in cramped cases, laptops or older computers can be difficult.
Modern SATA-style hard drives are usually much easier to replace than older hard drives that used the IDE interface, partially due to the smaller and more secure SATA cable design that replaced the finicky ribbon cables used on older drives. Computers designed as servers or workstations often have drive bays designed for easy installation with connectors for power and data in place. On these computers, a hard drive replacement only requires removing the old drive and slotting the new one into the bay.