This isn't just about "piracy". As far as I'm concerned, it's about freedom. As long as no one can dictate the food I eat, the time I can wake up, the things I decide to do every waking minute, no one should be able to dictate what I post or choose to see on the internet.
Still not sure what SOPA is and why I oppose it? A few resources:
http://www.geekwire.com/2011/where-do-you-stand-sopa
http://lawofthegeek.com/2011/12/04/lotg-004-shiver-me-timbers-a-sopa-discussion/
http://www.craigslist.org/about/SOPA