Where to download OLD 7.1 firmware?

I need to go back to "before" 7.1.1, since I am having huge problems with base station not giving IP to my WINDOWS machines. I have read a few answer (including http://discussions.apple.com/message.jspa?messageID=4771213#4771213 ) however, I cannot seem to figure out how to "downgrade". So... Is there any where/anyone that hold the "OLD" 7.1 firmware file? I need it really badly...