To answer your questions:
Cheap RAID 1 rebuilds?
Yes (as Cova pointed out so very well
) This is required for all RAID levels except RAID 0 (AKA Striping) and JBOD (AKA Just Bunch of Disks or Spanned Arrays). Even though these devices will "rebuild" failed drives, these cheap IDE solutions will probably not allow you to simply add another disk to the array and automatically include it in the already functional array. Like Cova pointed out, that is usually a function found in very expensive SCSI RAID adapters for mid-highend servers.
Barton OC?
Too early to tell if Barton will be a good OC or not. I would say that if you spend the extra money on the Barton, then just not worry about OC it. It should be fast enough for your needs
Otherwise if you feel like saving some money and getting something as fast or a bit faster with some extra effort, then go with the Tbred B CPU and OC. Thats all I was trying to say. BTW why spend extra money on a faster Tbred that will probably cap out at about the same speed as a 1700+ for less????
Ok anything else??