How to drive a DC brushed servo with PWM?

I've acquired a few brushed DC servo motors. These are basic, they take DC in two brushes and have a quadrature encoder. I want to use these with LinuxCNC. The PC can read the encoders either directly or via a Mesa FPGA card. The PC will also generate PWM and direction signals to control the motors. Again either directly or via a Mesa card.

So what else is needed? I figure a DC power supply that can supply about 50 volts and then "something" that lets the PWM control the power supply's 50V output. It seems that is would be just a basic dual H-bridge.

I could build a simple h-bridge but I bet there are better commercial ones available

I'm asking for suggestions. What make and model parts should I be looking at for driving mid to small size DC brushed servo motors using the PWM/Direction signals from either a parallel printer port of Mesa FPGA? I'm OK with buying used on eBay or new parts. Cost does matter as this is for hobby/education

Another option from CNCDrive.com Here . 160V / 35A and around the £100 mark. Is that beefy enough? I have one of these but haven't been able to try it yet.

Although you could take the encoder signal and output a digital PWM signal using a Mesa card, you would need to take care of all the hardware and protection as well as set up and optimise a positioner / PID controller. On the other hand, a servo drive takes care of all of that. I guess it would depend if you want to play at developing a servo drive or implementing a machine.