Hi,
There has been some talk of using only bipolars rather than a MOSFET and that might be fine too, but if you still want to use a MOSFET then that 1M resistor is probably far too large, if that schematic is still valid. 1 Megohm is too large to charge up the gate of the MOSFET if the frequency of the PWM is higher, but even with lower frequency PWM i dont think you want that high of a gate pullup because it will take too long to turn the MOSFET on. Maybe at the lower level current it will be ok, but it would probably be better to decrease that resistance significantly. If this is battery operated you may want to think about this more carefully but if not a lower value would be better in most cases. Remember that the equivalent gate capacitance has to charge up before the MOSFET will actually start to turn on, so whatever value resistance is in series with that capacitance determines how fast the MOSFET can turn on, and this is always something to consider with at least some care.