"If the port pin can sink 20 ma then why bother with the PNP? "

- Because a controller is good at deciding which LED to light up and a driver is good at making that LED light up.

- With MCU package sizes shrinking by the day, it is all the more important that you don't add to the thermal load by making the MCU drive LEDs, speakers and heaters !

- Use the 20mA as your safety margin in designing the port loading and use external drivers to handle the actual loads. You will never come to grief.

And finally if ALL that your MCU is going to switch is that one LED only, and you want the most simple hardware set up - yes do it directly. But still pay heed to the points Prahlad mentioned.

Raghu