You can also do this with the Maxtor drive. Another thing to consider with the dual drive units is this: if one drive goes bad (and you're in RAID 1) will the warranty allow you to replace the drive yourself, or do you have to send it back to the factory? WD allows you to do the replacement yourself, while Maxtor voids the warranty when you open the case.

I am the Doctor, and THIS... is my SPOON!