Thank you so much. I hexedit ur kext and my broadcom 5761(id1681) works perfectly under 10.6.3 64bit
it didn't work at first, then I found there's another applebcm5701 kext in the extension folder, i deleted that, hexedit the one in the plugin folder in IONetworkfamily, and it works!!!
What edits did you make to the one in the plugin folder in IONetworkfamily, exactly? I have the same NIC in my Dell T3500 and I can't get it to work.