I picked up a couple of these modules:
from Elecrow.com so I could attach (communicate with and control) several of my Arduinos through a LAN connection.
I have found (and you will too if you GOOGLE this module) that even though they say 3.3V input, they don’t work well at that voltage. They run perfectly when supplied by the Arduino 5V pin.
To run your Arduino sketch pick up a copy of the needed ENC28J60 library from Elecrow here.
Need more information or sample code? I found the best information about using this module is here: tweaking4all.com