Given that I've never had any problem with Slackware 8.1, I have no idea what the problem is. If you are running the "snddevs" script after building and installing the driver, and you are sure the modules are loading correctly, I am at a total loss. I've never attempted it with a stock kernel, but since the stock kernel has the soundcore module, I don't see why it wouldn't work. After attempting to play a sound file and failing, type "lsmod" and report on what modules are loaded. Maybe that could give a clue as to what is going on.