I also have an M6300 but with Ubuntu 7.10 64-bit installed (it seems that 64-bit version causes more problem). Unfortunately, the sound does not work at all. Did you succeeded in using sound card during your Ubuntu testings ?
I am using Ubuntu 7.10 64 bit. I followed the steps at the URL
https://wiki.ubuntu.com/Gutsy_Intel_HD_Audio_Controller, using method G
1. Enable the backport sources, you can do this by running
sudo gedit /etc/apt/sources.list and uncommenting the line
deb http://us.archive.ubuntu.com/ubuntu/ gutsy-backports main restricted universe multiverse
2. Then installing the linux-backports-modules meta-package
sudo aptitude install linux-backports-modules-generic
After that is installed,
3. sudo gedit /etc/modprobe.d/alsa-base
and add the line at the end of the file
options snd-hda-intel model=dell-m42
save the file and reboot
I was able to use the mute, volume inc and dec buttons afterwards.