It all depends on if the chunk of hard disk space that was holding that data has been wrote over. When you delete something it flags it as deleted so when you check my computer you see you have X ammount of disk space left (even though the data is still there). It'll stay there till you save something in that space. Once you do, it's gone for good. A good bud of mine did data recovery for the cops at one point till he went military. I'll see if I still have any of his apps laying around