The basic location of the machine enclosures, i.e., the CPU case, and monitor must be secure from being hit or knocked over. Make sure that all the connections are secure and screwed into the machine outlets. All users should take some care in keeping their machine secure from being stolen. Some care should be taken to keep the coffee out of the keyboard and Zip drive. Keep a can of compressed air handy to blow the dust our of the machine regularly.
Computers attract dust.
Security of the data is also making sure that the CPU case has enough air flow in it to keep the heat at an acceptable level. Most of the components in the CPU case generate heat. The CPU and HDD are great generators of heat. Nearly all CPUs now require a cooling fan. I only use cases which give me the choice to install extra air flow cooling fans.