Power transistors are spec'd for a fair saturation voltage loss of about 0.5V when their base current is 1/10th the collector current. The OP wants the circuit to work with 1A loads so the 2N390x driver transistor will need to conduct a whopping 100mA. The its base current will need tro be 10mA for it to saturate as per spec so the input to it needs is 10mA which many ICs (Cmos) cannot produce.audioguru:
This is similar to the circuit i was talking about. You'll have to find better values for the base resistors of course but we'll save four transistors this way.