Try this sketch. It tests the SPI bus and the SPI end of the w5100. Does it show 192.168.2.2 on the serial monitor? If it shows anything else, like 0.0.0.0, then check the shield connection to the Arduino. Insure all pins are inserted into the sockets.
#include <SPI.h>
#include <Ethernet.h>
byte mac[] = { 0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
IPAddress ip(192,168,2,2);
void setup() {
Serial.begin(9600);
// disable SD card if one in the slot
pinMode(4,OUTPUT);
digitalWrite(4,HIGH);
Serial.println("Starting w5100");
Ethernet.begin(mac,ip);
Serial.println(Ethernet.localIP());
}
void loop() {
}
BTW, the dhcp example I posted in Programming wouldn't work if you are connected directly to your PC. It doesn't have a dhcp server set up on that interface. That would have been helpful to know.