What is the name of your state (only U.S. law)? Colorado
... but I haven't actually downloaded anything. The ISP is however in my name. I checked my Comcast e-ail and noticed 11 e-mails from Comcast warning me of copyright infringement. I went through the e-mails and it is nothing I have downloaded. Should I be concerned?
I agree with both TheGeekess and CdwJava. There is reason to be concerned whenever you receive a notice of infringement - and 11 notices of infringement puts you at risk of, not only termination of your ISP service for a violation of their terms of service, but also puts you at risk of a copyright infringement suit. These infringement notices are not something you want to ignore.
Whether your roommates illegally downloaded movies or music, the following March 2014 Recording Industry Association of America (RIAA) link on illegal music downloads provides good information on what anyone should do when in receipt of a copyright infringement notice from their ISP:
http://riaa.com/toolsforparents.php?content_selector=resources-music-copyright-notices
Currently it is the movie industry that is most aggressive when seeking out and suing copyright infringers. Settlement demand letters may be sent but, increasingly, many movie companies are skipping the initial demand letters and filing suit against the infringers, with requests for jury trials.
Should you receive a summons and complaint for infringement, you will want to consult with an attorney in your area and respond to the complaint within the time allowed. An actual infringement suit can get costly quickly, as CdwJava noted, and, as CdwJava noted, you should take steps immediately to prevent any further infringement by your roommates.
Good luck.
