Greetings, I managed to get it to work, thanks to your tips.
Following the instructions in MPlayer's website [1], I built mplayer with ffmpeg-mt (multi-threaded ffmpeg). Playing 1080p movies with two threads (-lavdopts threads=2) they play as smooth as they can get.
Meaning that even without a vdpau compatible card, a decent enough CPU (2,4 GHz in my case) plays 1080p without cutting down on quality.
Thank you everyone, Paulo Santos [1] http://www.mplayerhq.hu/design7/news.html
