You need 4 drives for a RAID0+1 array, with 2 drives you can only choose for RAID0 (speed) or RAID1 (reliability). And no you have to backup your data and restore later, because creating a RAID array makes the previous data inaccessible on those drives.
Intel Matrix RAID might be able to do it, i never used it. But that only works if you got an Intel ICHxR (R = RAID support) chipset, like ICH9R or ICH10R. If you have such a chip, go read if it can do what you want. If not you're out of luck.