@wabsta your IP can be found if law enforcement/similar ask with warrants and all of that but if you downloaded something from usenet and got done for it as part of the series of events then you would be the first. Even then you are more likely to be tripped up by a false flag/honeytrap NZB site (something I have never seen) and that would be incredibly hard to do anything with too (the same reason you have to actually appear in a swarm not just download the torrent file).
http://www.giganews.com/legal/tos_personal.html is fairly representative of usenet providers- unlike your torrent sites these are fairly big companies (they do deals/provide services to national ISPs after all) with serious resources so they are not likely to buckle under a few simple threats.