Because you installed Snow Leopard in the first partition. Now, that becomes dead space. In disk utility, once you set a partition scheme, only the first one is malleable. The second one cannot be resized, so you're out of luck. Maybe this is also the cause for the persistence of Snow Leo's old Chameleon.

By the way, when you installed Snow Leopard, you remembered to disconnect the Windows drive before doing it? Because maybe the old chameleon you see is the one that was installed in the Windows drive in the case you forgot to disconnect it, so you would be again out of luck. When installing OSX, and specially installing chameleon, always disconnect your Windows and other OSes disks.