Hi,
Note that I said - If the timer is driven with a frequency of 1MHz - which it would be if you run the PIC at 4MHz and select Fosc/4 as the PWM Timebase input.
Apart from that you are correct. If you'd run the PIC at 1MHz and set the PWM timebase to derive it's clock from Fosc/4 then the timebase will run at 250kHz and you'd get a PWM frequency of 1655.5Hz with the values in the previous example.

/Henrik.