I have two WDC 500Gb drives in RAID 0. I was under the impression that data is duplicated and therefore I would have 500Gb usable space. However windows is showing 931Gb space. Is this right?
Raid 0 is a striped array. Simplified you get the capacity of both drives. It just splits the data between the drives for faster read and writes. If you want to duplicate your drive then you want raid 1.