If you have two HDD's present in your system then yes of course, but you might want to check your mobo manual to see if there is a raid controller on there.
if not you can always buy one online somewhere.
however you can only create a raid 0 setup with two empty and freshly formatted hard drives.
also keep in mind that raid 0 has no fault tolerance, so if one disk fails you entire system fails and all your data will be lost.
So I'll advice you to buy either an extra HDD or an external one to backup your data.