From Mary Ellen Modica, PT, MHS, and a Physical Therapist for 22 years:
The workstation must be customized for the individual. The chair should be
adjustable with 5 casters, upholstery and a water fall edge so there is no leg
pressure. It should be adjustable for height and seat angle. The chair is
adjusted so that the elbows are flexed to 90° and the wrists are in neutral.
Wrists should rest on a keyboard wrist rest and a mouse pad should be used to
decrease any pressure on the wrists. The top of the monitor should be at eye
level. There are risers available at office supply stores, but the hard drive
or even telephone books can be used to achieve the correct height. Feet should
rest on the floor. If this is not possible after adjusting the chair, a
footrest can be used.
The OSHA website has some helpful information and advice at the following
link: http://www.osha.gov/SLTC/etools/computerworkstations/index.html