In order to create an array you'd have to reformat.Your best bet would be to put 2 drives in RAID0, and then copy data from your existing drive as you see fit, after you've installed windows on the array.Then, you can add the third drive to your RAID0 array and expand your partition to take advantage of the additional space.Side note: I would not recommend using more than two drives in RAID0. If a singluar drive fails, you lose ALL data on the entire array. The risk of failure increases exponentially the more drives you add into a RAID 0 array. If you want a bit of redundancy, I would suggest RAID 5. You lose one drive's worth of capacity, however if any singluar drive fails, you retain all of your data. Once you replace the failed drive, the array will rebuild itself onto the new drive and you will once again have a failure tolerance of one drive.