PWM 180V DC Motor Speed Control

Hello, I'm hoping to control the speed of a 180V DC, 0.44kW motor using PWM optoisolated from a PC parallel port. Essentially I would like to convert that pwm signal to a varying voltage.
Am currently looking at smaller circuits to get an idea of how this works.
I'm gonna keep reading up - hopefully work it out - new to this but it looks fun.

Ok, so now I know what triacs are. I've also read that they need to be used carefully, can cause problems with microcontrollers and alike, messing with power source.
I've looked at what triacs I have available to me, such as the BT137. But I do not have any similar designs for a voltage regulator using a pwm signal.

Edit: Time for bed, I'll carry on in the morning!

Triacs are usually used for controlling AC not DC.
They need the volts across them to go to zero to switch off.

You could use a PWM into a FET amplifier buffer to control the DC voltage but it would probably need a big heatsink.

Yes ok, big heatsinks are nice. Let me go find out what that is...