Art,

That circuit should work except for the following.

1. You need to really pull the gate to ground. You sort of attempted this, but you should do it by either tying the 5k1-SW junction directly to the gate (probably not too safe, but proves the point). Or tying it through a resistor (as you did), or using a voltage divider (Battery-Resistor-Gate-Resistor-Switch). The gate vs source resistor ratio (note they form a voltage divider) should be very low. In other words, when the switch closes you want the gate to see as close to ground as possible.

2. Make sure you're using a P-channel MOSFET, not N-channel. More so, make sure the device is meant to operate from logic levels (i.e. you want a logic level MOSFET).

3. You could use the same RC time constant in the second picture and it would give you additional delay. Capacitor goes on gate (to ground), resistor from gate to SW as small as possible, resistor from gate to battery as large as possible. This should give you a fast discharge rate (for turning on) and slow charge rate (to allow uC to take control).

4. You could also use either the second circuit shown, or Melanie's. Both very elegant solutions too.

Hope this helps any,

languer.