Last week I setup dual boot on my Laptop for giving Gnome on Debian a try. Worked without any problems, except the sound, the driver was installed correctly, but still had no sound. After reading loads of docs I found the hint of using the Realtek Code-Software here. Here step-by-step what I needed to make it working:

get_build_packages

apt-get install linux-source linux-headers-3.0.0-1-all-amd64 build-essential

get file from realtek - choose your kernel

become root

su root

uncompress file (example!)

tar -vxjf LinuxPkg_5.17Beta.tar.bz2

change to new dir (example!)

cd realtek-linux-audiopack-5.17

do the installation and reboot

./install
reboot