The only thing that this should change is the sse3emu, so if your cpu has sse3emu, I doubt you will notice a difference. I believe that if you have a cpu that has sse3, you shouldn't change to this, as it won't change anything.

People with Snow Leopard on sse2 only cpu's: please update to 10.6.6 and try this out. Let us know what happens.