With the quadcore, key clone has the ability to set the affinity of running wow on one of the cores, so youd set your main wow to core 1, 2 alt wows to core 2, 2 alt wows to core 3 and the last one youd save for other programs such as music or fraps or anything like that. Dual core youd have to spread the wows over two cores and also share those cores with any other programs. Now without third party software WoW will set its own affinitys to the first two cores and you'll be wasting the other two.