Smooth Stepper is a good idea with a laptop. Waiting for Mach4, maybe not so good.
Have a look at the Mach4 update page:http://www.machsupport.com/software/mach4/
My understanding is that, depending on your hardware, Mach4 could be available to work with your machine soon, later, lots later or never. Of course, I could be understanding things wrong. You might talk to your machine / controller vendor to get a better idea.
Mach3 does everything I need. I can't see any reason to upgrade to Mach4 with my current machine. But, that's me. Everyone will have to figure that out for themselves. Take a look at Mach3. It might be all you need and it's available today.