help with cadsoft and rgb multiplex idea

are there enough pins from the arduino to hook them up directly to anodes?

I seen the idea of hooking the UDN2981A, but another guy recommends M54564P since it has a faster turn-off delay to avoid ghosting.

http://arduino.cc/forum/index.php/topic,18464.15.html

whats the idea of hooking the source driver to the anodes?

when you can directly hook them up to the atmega chip in the arduino to control them?