I've got a relative with a four-cour AMD Phenom II 3.0 gHz CPU (can't remember exact specs) and ATI 5750 1GB graphics card, running Ubuntu 10.04.
Right now I am aware of VLC and Mplayer for playing video files. But when playing 1080p mkv files, etc., the video stutters and lags pretty badly.
Are these media players taking full advantage of the multi-core CPU and graphics hardware? Is there a software tweak, or just another video player that I could try?