You didn't mention the drives, but they need to be identical for a striped array. They also need to be configured together as an array before you install the OS.
That being said, given the cost, you'd be much better off spending your money elsewhere, as RAID0 on a desktop is nothing more than hope and hype. Add in the increased rick of data loss (3x in your case) and it just isn't worth it. Some will even tell you that seek times take a hit on an array, causing slower performance in certain areas of Windows usage. It was used early on to overcome the small size of SSDs, but now that they have fallen in price, the usefulness of RAID0 has pretty much pulled an Elvis, and left the building.