HOW-TO: Setup Multimedia on Ubuntu
 

The most annoyance I had from switching to linux was multimedia (setting audio/video codecs properly) and thanks to everybody in this forum I was able to put together an absolute beginner's guide on multimedia setup at twentyplus.blogspot.com (written by a newbie). I thought it would be great to share this information and have other newbies cut down on their 'how do I configure Ubuntu to play audio/video files' time. ;)

Also check out ubuntuguide.org - it shows you how to do everything including MP3, DVD, DiVX, Adobe, plugins and a lot more.

Or the official wiki and forums for Ubuntu ;-)