Hey there, i need some advice here... i download a codec for windows media player, i am able to play RMVB files, but!! there is no audio coming out... any suggestion??

IT would be easier if you are using mpc-hc. i can play RMVB without codecpack installed except ffdshow.
but the guide is a little bit complicated if you arent familiar with mpc-hc.

Try this player first if you cant wait to watch your video
http://smplayer.sourceforge.net/

yes...agreed..

or just use VLC,no need to install external codec...internal codec also necessary to play full hd video..

if u don mind, i would suggest u to try thekmplayer + real alternative codec, it's realy a gd player n u can ply most of the files extention wit tat combo.