The review mentions that its a 60GB/platter design with 3 platters, which would only be 180GB rather than 200GB, and it also goes on to say that it might actually be more than 60GB/platter. It should be aroudn 66.7GB/platter then.
Also, it says that there are 2 versions of the WD1200JB - one with 40GB/platters and another with 60GB/platters, and that the larger density ones are from Sep 2002 onwards, that's like only 1 month ago. Does that mean that all older WD1200JBs are based on the lower density platters and therefore slower?