ATI Radeon X600 XT

My Card worked fine in Tiger, but Leopard seems to have deprecated support for the Intel ATIRadeon9700 / ATIRadeon9700GL kext that my card uses. I was wondering why this is, and what can be done to get graphics acceleration (ie. Quartz Extreme) working again on my mac. I have tried using the drivers from Tiger with no success.

Why would apple remove Intel support for an otherwise functioning driver set?