*EDIT* Beaten to it, but I'll say my piece anyway.
Essentially SOPA and PIPA will give the US the right to shut down websites and demand data from them regarding individuals accused of breaking copyright laws. It sounds sensible in principle, but the devil is in the detail: As well as folks who download films via torrents, it could also be used to stop sites like Wikipedia quoting sources or linking to websites that might themselves then link to somewhere that distributes naughty stuff. In short, it gives the Man (sponsored by the film, record and gaming industries) freedom to do whatever he wants to whatever he wants, whenever he wants. It's a vastly bloated piece of legislation that is too over-reaching in what it would allow the US government to do.
Whilst it might not affect any companies holding data outside the US, how many websites do you use that are based in the US? All the big ones could be shut down overnight, and then once other governments see how easy it is to implement it will start getting bastardised abroad, much like our own people in charge have done with the law that makes ISPs give details of potential file sharers.
As ever with these things, it would do very little to prevent file sharing but would inadvertently give power to get rid of the irritating itch in the Federal back. It would be so much easier if people just stopped downloading stuff for free, but that's another debate that always ends up with them saying "But I wouldn't buy it anyway so they're not losing out!", which is a poor way to describe theft IMHO.