If you need 8 bits of resolution, your PWM clock needs to be 256 X 200Hz = 51,200Hz. That is pretty fast for software.

I would choose a PIC that has 4 or 5 channels of PWM (18F8722 for example). With that part, you can "set and forget" the PWM registers. Everything would happen in the background, and there would be no issues or conflicts with HSERIN.