Installing new Firmware on Wifi Shield

I have been playing around with the arduino and decided to have a go at the Wifi shield. I have tested it out with the WifiWebServer example, it all seemed to work but the IP address produced nothing.

I researched and as I am running IDE 1.0.5 I need to flash new firmware to the wifi shield.

I tried to follow the instructions on the Arduino page ( got as far as entering :

batchisp.exe -device AT32UC3A1256 -hardware usb -operation erase f memory flash blankcheck loadbuffer /Arduino/hardware/arduino/firmware/wifishield/binary/wifi_dnld.elf program verify start reset 0

in command prompt and then it went wrong. Comes up with [u]AtLibUsbDfu.dll not found[/u].

I have looked at so many different ways to fix it but nothing is working.

Is there someone who can give me a simple explanation to fix it?