no idea, dont know how many games you have. i say use an entire seperate drive for it, less faffing around.
the problem with trying to create partitions for everything on one drive is that you inevitably run at of room on one of them, then you have to start mooving films around, changing partition sizes ect....its too much hassle imo. if you put it on a seperate drive (i mean, whats the cost of a 500gb drive these days?) then at least if you run at of space you can just buy a bigger drive, transfer the lot and use the existing drive for something else. minimum effort