The 160GB Maxtor's all formatted to exactly the same size, which surprised me after the problems I had with the 705 and the Quantum drives. To be honest, the drives are a little different, the labels of 2 of the drives are different but the model number and capacity are all the same and the physical appearance is identical. Hence my surprise when they all formatted to EXACTLY the same size.
I looked in the old posts on this forum and found another person with the same problem. He was able to make a raid-5 using THREE of the four drives with no problem. From reading his posts it sounds as if he was having the exact same problem I am having!
http://forums.procooling.com/vbb/showthread.php?t=13528
I am going to try building a RAID-5 out of 3 of the drives, and see what happens.