XBMC is an open source media player for Linux, Mac and Windows. XBMC 10.0 code named Dharma has been released and now has addon support.
Hardware acceleration has been added in windows (Vista or 7) via DXVA2, CrystalHD has been added for all platforms (best supported in OSX and Linux), VDPAU support has been improved in Linux, and VAAPI support has been added for the hardware that supports it in Linux
Installing XBMC 10 on Ubuntu is fairly easy.
[sourcecode lang=’bash’]sudo add-apt-repository ppa:team-xbmc/ppa
sudo apt-get update
sudo apt-get install xbmc[/sourcecode]