Raid 0 is a striped set, that may increase the speed since the reads and writes are distributed over the number of drives. The amount of space available will be twice the size of the smallest drive of the two WD Raptors. The failure rate of a two drive array is a little less than twice the rate of each drive for a two disk array. There is no data redundancy so if one drive fails you data is not easily recovered so always maintain a backup copy of your data. You can Raid 0 two different WD Raptors. It will work.