I've been watching "My Cat from Hell" on the animal channel recently. Most of the time he solves problems of kitty territorial struggle (I'm assuming that's your problem. Both cats are fixed, right??) by giving them access to high ground. Stepped shelves, window ledges, chair-shelf-furnituretop paths that lead to a comfy spot to survey the field. Hopefully, if they each find a spot on opposite sides of the room, there'd be nothing left to fight about.