Pledge against DRM

Here is a pledge at PledgeBank that proposes that "I will pledge to never purchase a CD containing any form of Digital Rights Management (DRM), but only if 500 people around the world will too." I have signed this as I generally dislike the practice of a company telling me how I can use my technology (I do have two Linux machines). I am also concerned about the privacy and security implications of technical protection measures as exemplified by the Sony case.

However, I wonder if threatening a boycott will really change things in the industry.