I think the problem stems from the fact that the game was developed for cards in use around 2005 (as well as being ported from the xBox).I'm not sure on this one, but didn't ATi do the graphics for the xBox systems? If so, then there shouldn't be any issues

As for the diamond shaped raindrops, the raindrops are rendered as 3d raindrop shaped objects, but obviously the refraction shader doesn't seem to be working. Not sure what caused this in the final build of the game but I prefer the older raindrop effect (2d sprite bubbles appearing on the screen) used in earlier copies.