So I've just "up"graded to 10.5.6 and the 9600 card seems to not be working under it. The entire external monitor had blurry lines, basically it seems like each vertical line was replicated a few lines next to it so that separate lines are overlaid on top of each other making everything look horrible. The problem occurred after using it for ~5 minutes. Now I'm on the 9400 card and so far things are working OK. Please post here if you have the same problem or have heard of it.