dsicon, I have used a MAX1724 in the past with 2 diodes on the output (anodes), 1 cathode going to the load and 1 cathode going to the PIC VCC. Connected to the PIC VCC I had a second diode cathode connected. The anode of this second diode went to the battery source. The battery source was 2 AA batterys in series to give about 3 volts. This provided low power to the PIC and when the PIC awakened it placed + 3 volts on the shutdown pin of the MAX1724 which turned it on. This then produced +5 volts to the high current circuitry (100 Ma.) @ 4.5 volts (thru a diode drop). This switching regulator will work down to 2.6 volts on the input. There are ways to shin a cat at 2.6 volts.....

Dave Purola,
N8NTA