Linux mint is a good start in that it has a lot of the codecs you need already part of the install. I am using the Karmic Koala netbook remix and have had no problems it actually only needed just the restricted extras and the medibuntu packs to read and play all media. I always install Ubuntu Tweak on Ubuntu installs due to it is a easy way to get the 3rd party repositories and keys in one fell swoop. I have seen that the Koala release is already set up pretty well with the needed codecs but I just automatically install the extras and medibuntu stuff.