Links is hardly a bad game, It's severely underated. I enjoy it much much much more over Tiger Woods as it is most realstic. The only thing that sucks is only four people can play at once online, but do you really want more then 6 people anyways?
Rivals on the other hand is pretty bad, but give MS a few years and they should work out the kinks. The pick up mode however is unbeatable, not even ESPN Nhl Hockey can match the pick up mode. Basically you play one character while each other human player plays one as well, and the goalie is the only one controller by the cpu. It's hellah fun.
I would pick up both at $20 in a heartbeat if your into XSN and only own a XBox.