Well if you are convinced about the Mac, Snow Leopard will not make you change your idea and vice versa, Snow Leopard is just a refinement of Leopard, for me the most important thing is the switch of many applications from 32bit to 64bit which will increase their speed something around 2x. for many others they care about the support of Microsoft
exchange but I don't use it.
In addition to these two major things, they refined almost all the OS applications adding more helpful utilities, if you are interested about all the updates visit this
link