edit: I'm 99% sure that my congressman, Jim McDermott, is opposed to SOPA, but I just called his office to make absolutely sure. It only took me a minute. PLEASE PLEASE PLEASE call your congressperson.
While this means that I don't have to call her office to "change her position", I will still call to thank her / her office for being a vocal opponent of SOPA.
edit: Also, thanks to the HN users who have posted in other threads asking others to call the offices just to voice their support for their representatives, even if the congressman/congresswoman is already against SOPA. Without their words, I wouldn't be calling my representative today to say thanks.
[1] http://eshoo.house.gov/index.php?option=com_content&view...
Also, be sure to ask about Protect IP (S.968): http://www.opencongress.org/bill/112-s968