Forget just the chair. You need an ergonomic work station. One that not only includes a chair, but also an appropriate desk, monitor stand, an articulating keyboard/mouse tray and an adjustable foot rest. One of my auxiliary duties at my company is evaluating workstations for deskbound employees and showing them how to adjust their workstations to alleviate neck, back, wrist, and leg stresses. As a young buck (judging by your picture) you may not appreciate this, but after several years, these stresses take their toll on our bodies. I've had carpal tunnel surgeries on both wrists and have a herniated disc in my back. A lot of back/neck/hip/knee problems stem from our activities outside work and are further aggravated sitting in front of a monitor for several hours a day.

Here's a link to get you started: http://www.osha.gov/SLTC/etools/computerworkstations/

Good Luck,

Steve Tahan