Below are some of the popular media centers for Linux
LinuxMCE is a free, open source add-on to Kubuntu including a 10' UI, complete whole-house media solution with pvr + distributed media, and the most advanced smarthome solution available. It is stable, easy to use, and requires no knowledge of Linux and only basic computer skills.
XBMC is an award winning media center application for Linux, Mac OS X, Windows and XBox. The ultimate hub for all your media, XBMC is easy to use, looks slick, and has a large helpful community.
Mythbuntu is an community supported add-on for Ubuntu focused upon setting up a standalone MythTV based PVR system. It can be used to prepare a standalone system or for integration with an existing MythTV network. Unlike similar projects, Mythbuntu keeps close ties with Ubuntu and all development is given back to Ubuntu. This architecture allows simple conversions from a standard desktop to a Mythbuntu machine and vice versa. The development cycle of Mythbuntu closely follows that of Ubuntu, releasing every six months with Ubuntu releases.
MythTV is a Free Open Source digital video recorder (DVR) project distributed under the terms of the GNU GPL. It has been under heavy development since 2002, and now contains most features one would expect from a good DVR (and many new ones that you soon won't be able to live without).
Pick your choice 