For movies and Xbox, they might not be so bad because you would probably be sitting fairly close to them. I've heard good things about those speakers.
However, like the others have said, they likely won't cut it for a party in a room that size (with 50 people chatting) unless you aren't looking to fill the whole room with music. If you want a small dance area with music, while the other end of the room can hear it but not really loud, then maybe.