What you would want to do is encode different methods (product ID, hard drive serial, etc) separately and then encrypt them together in such a way that the program can decrypt and split them so it can check them individually...of course, that's if you want to secure against problems if the user does make minor changes to their computer (and you would then need to also write in code to modify stored data and re-encrypt it all)

What you could do is store serial numbers of the different methods and encrypt them then on startup the program collects the serial numbers and compares them to the encrypted ones (decrypt first, obviously)

It's all up to you, really...I'm more an ideas person; I know these things can be done and I am good at working out how to do them (theoretically) but in practice I'm about as useful as a chocolate teapot if I have to actually code them :-)