Since this is located in the security section of this site, I presume you are looking for ways to make your hardware physically secure. It is not possible to completely protect the system, as most computers can be tucked under the arm, walked off with, and forced open later. A case protecting the hard drive from tampering is not particularly useful if the entire system can be moved to another location for disassembly. The most effective way of protecting the drive is to install it in a removable, plug-in caddy and take it with you when you leave the system. The removable drive can then be stored in a secure location, such as a safe. This method is commonly used to protect sensitive materials. If this is not an option, you need to secure the system itself against theft or intrusion. There are secure cases in which the entire computer can be placed. The security case is then attached to something solid like a desk or a wall, so the thief cannot easily walk away with the unit. Some of these are designed in such a fashion that the system is difficult or impossible to dismantle on-site. There are cable locking systems that can be used to secure the computer case to a solid object, but these do not protect the system from having someone dismantle it on-site. Industrial rack mount computer cases are more secure than desktop cases, as they are used in 19" racks that are bolted to the floor or are inside large cabinets. Bolts with one-way heads or similar fasteners can be used to install the system. This will hinder removing the systems from the racks, slowing a would-be thief. There are various types of case locks available, but these do not prevent someone from walking away with the entire unit. They are only meant to deter someone from, for example, opening an optical drive. Electronic alarm systems are available that will signal the removal of a system from a site. Individual components inside the computer may be tagged so that their removal from the site can be detected, in cases where the computer is dismantled on-site. In general, though, most thieves want to work as quickly as possible, so anything that may slow them down can make them turn away from a protected system to an unprotected one. But if the thief really wants the data on your hard drive, the best defence is to remove the drive and store it in a secure location. Just about any case can be quickly forced with a pry-bar. There is also the issue of data security. If the system is physically well protected, an intruder with electronic access - at the console, over a modem, or over a network - may still be able to transfer data to or from it over a network connection. High security systems are often not connected to any kind of phone line or network to avoid this risk.