PWM vs. DAC?

Hi,

I've hired an electronics man in Russia to produce an S-Curve
controller for a hydraulic robot project. He says PWM (Pulse Width
Modulation) is much more efficient than DAC (Digital to Analog Control)
which I'm more familiar with to run the valves. The recent failure of
my MaxNC to respond to my computer makes me consider integrating a CAM
retrofit into this project if PWM is also good for servos. Is it?

I've also been told plain bushed DC motors are just as good as servos
for robot/cnc use but I don't know if they'll also work with PWM or
need DA. I want to specify hardware that works for everything with
only software changes. I figure DA could be programmed to do PWM
through a PIC but I'm trying to think a little over my head here.
Advice?

Thanks,
Kirk Fraser
Clatskanie, OR