Rice may be old but he can still catch the ball. He's not going to be a deep threat but for the short gains he's one of the most consistent receivers. As a Raiders fan it's sad to see him go but he wasn't doing anything this season so at least he gets to go to a team that actually will use him.
Now as for Jerry Porter, there is no way the Raiders should trade him. It's not his fault Kerry Collins can't throw for shit the past couple of games.