How to protect my soft in CD or DVD against piracy ?

The only real way is to do this:

0) Maintain a registration database server that contans all valid keys, whether or not they've been activated, and on what machine (see note below)

1) Force the software to require an internet connection (so it can check the remote database to verify the installation), and if one isn't available reduce it's functionality, or don't allow it to run at all.

Identifying machines is an iffy proposition because there's no real way to concretely identify a machine. MAC addresses can be spoofed, hard drive serial numbers change with every format, and the CPU ID thing only identifies th capabilities of the CPU - not the CPU itself.

In the end, copy protection is a waste of time for everybody involved. It adds production costs to the product, raises prices for the end user, and is seen as nothing more than a minor challenge for people that would crack the protection scheme simply for the sport of doing so. Consider that Blu-Ray copy protections are usually cracked within 24-48 hours, and you'll get a sense of the futility of trying to protected ANY software product.