OK, issue solved (the drives were in RAID).
So I tested the WD with HD Tach. There are to tests: 1 with 8Mb and 1 with 32Mb, whatever it means. The 8Mb test has a STR of 67 Mb/s in the beginning, avg. of about 55. The 32Mb test has a STR of 76 Mb/s max, and avg. of 60.8, burst 205.9
So what do you think, is it a 160Gb platter?