using avr atmega32 as web server using ENC28J60 chip
avr-uip http://code.google.com/p/avr-uip/ is a port of the free UIP network stack to the AVR, it has a driver for the ENC28J60 and a web server example.

To simulate the system on a PC, I'd recommend trapping ethernet frames at the point of entry/exit from UIP.