Piracy is just a way of life, Just Focus on making quality applications and people will buy it regardless.
Microsoft, Adobe, etc.. Spend Millions of dollars trying to stop Piracy and they fail miserably. (And to me putting all that anti piracy (Serial#, Online Activation) just puts more pain on the paying customer. The pirated version is better than the retail version because all those hassles of activation,etc.. are stripped anyway.
This is One of the reason i love apple, most of there software products don't require a serial or activation. Most people are honest and Apple understands that if you make quality products people will buy it and you are going to make money regardless.