Funny you should metion Realtek, I was just at the ASUS site looking to see if I had the latest BIOS when I saw that ASUS released a Linux audio driver
for my A8N-SLI Premium(nForce4 chipset), this driver as well as the win drivers are labeled as Realtek audio driver. Upon futher inspection of the driver download they have I noticed two things, first of all its just the alsa-driver package with a couple of how-tos to get it working and second of all while looking at the supplied modules.conf file it shows this
#--- Intel 8x0 , SiS 7012 and NVidia----------
alias snd-card-0 snd-intel8x0
options snd-intel8x0 index=0 id="ICH"
So I guess, according to ASUS the offical Linux dirver is the intel one.