Do I not need, maybe need, or obviously need a buffer for this circuit?

I have an Arduino microcontroller that is sending out three digital signals, ground, and +5v to four groups of four 595 shift registers.  Each group will control 32 LEDs.

The arduino and the power supply is in a rack, and each bank of LEDs, and their four 595s will be on the other side of a 20' DB-25 cable. 

Do I need a buffer between the digital pins out of the arduino when each pin splits into four?  Can anyone point me to a simple buffer circuit to accomplish this? 

I am doing this project (except using four 595s instead of two):
http://www.arduino.cc/en/Tutorial/ShiftOut

Thanks guys!

are you building on perf board;

the 595s will be on perfboard.  The LEDs are P2P

No, four gates won't be a problem for an Atmega at any speed.