I'm fairly certain a GTX 560m will not work. From what I've seen your best two options are another GTS 360M or possibly a GTX 260M. If you can find them, make sure they are pulled from an Asus laptop or the will not work in yours.
From the few posts I saw most said it should be faster but it will also run hotter and use more power. Google around and see if you can find some reviews.