No. You can't do this. HOWEVER, you *can* run RAID 5 with 3x HDDs, this will give you data protection (in theory) but will loose performance. And usually, most boards fail at doing RAID5. Even if you DO get another HDD, you will be limited to 1-1.5TB with RAID10/1.
Raid 0 is not a true RAID. I have done 4 HDD in RAID 0 for my gaming and it's fast but it doesn't last long. The 500Gb drives are the best to RAID, I don't recommend 1Tb or higher than that, once this drives gets busted lots of data goes to waste.
I have tried Western Digital Black and Blue at 640Gb in RAID 0 and it's good one. It is also a good idea to put a cooler in your hard disk.