I have one, it wasn't on in the pic though. I didn't really get it solely for blocking radiation, but more for deturring glare in my old room.
The loud sound is caused by a degaussing magnet that encircles the picture tube of the monitor. The magnet neutralizes any stray magnetism that the monitor has picked up. New monitors project less radiation than older ones that are not TCO compliant. Read this for more info: http://www.closerange.com/working_solutions/TCO.html . Like I said, studies have been inconclusive on whether or not phones, monitors, power lines, microwave ovens, radar, etc... cause health problems. The real problem is that most, if not all, studies only look at a single radiation source rather than all sources combined.