I tried following the directions in this thread for Windows 7 64-bit, couldn't install the 540a version until I set compatibility to XP SP2 contrary to the OP. After I installed the drivers over the generic, working driver that Microsoft'd downloaded for me my sound stopped working, and then I tried installing the other version listed in the OP and it still didn't give me any sound, so I uninstalled all of my sound card's drivers/the actual device from the device manager, restarted, installed the generic Windows one again, restarted, and my sound still didn't work. I've spent the better part of the night trying different combinations of driver installs, removing my sound card from my case and a system restore to an earlier point in the night because I'd done so much tinkering with the drivers that I didn't have any restore points left that were from earlier and my sound still doesn't work. Would anyone have any ideas for something I could do? I feel like my only option is to reinstall the entire operating system.
Edit: huh, I tried plugging some headphones directly into the sound card's green jack with the Windows drivers and get sound. I wonder if my receiver just conveniently died.
Edit: OK, just pretend this post is asking has anyone been able to get output out of the back surround port in Windows 7 64-bit?