I'm trying to figure out which codecs I need to install in order to play Windows Media and encrypted DVDs with Xine. I believe these are universal codecs but I'm not sure... I think the codecs for the Windows Media are called w32 and the one I need for encrypted DVDs is css. Not sure where they're located though.

Since you have Libranet, you can use apt-get to install the codecs.

Add this to your /etc/apt/sources.list:
deb http://marillat.free.fr/ unstable main #replace unstable with testing or stable, whatever you prefer

Then do:
apt-get update && apt-get install libdvdcss2 w32codecs


Here are some more multimedia packages you might be interested in:

apt-get install avifile-utils avifile-mjpeg-plugin avifile-win32-plugin mpeg2dec avifile-player avifile-mad-plugin avifile-vorbis-pl ugin avifile-xvid-plugin toolame mjpegtools quicktime-utils libquicktime1 libquicktime-dev transcode gtranscode video-dvdrip xvid4conf subtitle2pgm rar ogmtools dvdxchap vcdimager

And MPlayer (note you must choose either mplayer-686 or mplayer-k7 depending on your CPU)
apt-get install mplayer-686 mencoder-686 libggi-target-emu libggimisc2 libggi-target-x mplayer-fonts