Not enough information to say whether you are stupid. But you sure need to work on your question posting skills. I have seen two posts from you recently where you provide far too little information to give a good answer to your question.
you have a spare x-25v, and you want to relace your single x25-m with 4 x-25v's in RAID0?
as long as you intend to buy 3 more x-25V's, then you atleast can do math. i dont see any problems with doing that hardware setup. if you want to automagically turn one drive that you have into a 4 drive array, then yes you are stupid.