First of all the partitioning might be the problem here. There should be now partition on the disks! Creating the raid0 will write a new boot record to the disks and so they will be empty after that anyway. You create the partition later while installing the os or initializing the volume in disk management.
Concerning the performance gains: you will see an increase of the transfer rates in benchmarks, but only in benchmarks. Unless you are frequently moving very large files (> 1GB) around, that doesn't matter for the real world. What matters is the very fast seek/search/access time, compared to hdds. And that stays the same in raid0 and even with sataIII. The downside of raid0: if your mobo or the raid driver or one of the ssds fails, you will never get your data back!