Any reason why? Just saying no doesn't help me in the least.
If you stripe two hard drives in RAID0, you gain twice the speed, but half the reliability, so your drives are more likely to fail. RAID0 works by writing to the two disks alternatively, so you might think if one fails you'll still have halve your data on the other drive, but you don't, because the data will not be usable. It's better just to buy one big fast drive. I assume you mean RAID0 when you say 'RAID', there are other RAIDs as well, but RAID0 is for speed. RAID1 is for backup, that works by writing the files to both drives so if one drive fails you still have all your data on the other drive because RAID1 simply copies drives.