How to Recognize Hardware

I am looking for a way to create a good protection for a program I am going to sell, maybe u know a way. I think the best way is to recognize the destination computer and check if it is the same one each time the program is loaded. My question is how to recognize a computer or one of its hardwares(HDD for example)?
I believe I am lokking for HDD/FDD(or other hardware) ID that can not be change. Please do not refer me to the VolumeID, because that one can be changed...


Form Niztan Aviram.
Any help whould be highly appreciated.