Ubuntu Studio supports serious audio, adds little for video and graphics
Ubuntu Studio bills itself as the "multimedia creation flavor of Ubuntu," an official Ubuntu project "aimed at the GNU/Linux audio, video, and graphic enthusiast as well as professional." It is certainly flashy on the outside -- even if it is mostly the same Ubuntu Linux distro under the hood.
Ubuntu Studio's first release is 7.04 -- the release number indicating that it is built on top of standard Ubuntu 7.04, although it was in fact released later, at the end of May. This version is available only for 32-bit Intel architecture. You can install it by downloading the DVD ISO image, or you can convert an existing Ubuntu 7.04 installation into Ubuntu Studio by adding the project's APT repository.
That repository gives you access to a dozen or so new packages -- some containing just a single application (such as the digital recording suite Ardour), and some containing multiple tools.
Because of its non-free status, video editing app Cinelerra is available through a separate individually-hosted repository -- at least such is the plan. I never got the repository to work, nor the parent domain to respond to HTTP queries.