help with HDMI

Hi everyone,

I need some help. I connect my Toshiba M300 laptop to my Samsung Series 6 LCD TV with HDMI cable. The video is great. But there is audio problem. If I play a DVD from the laptop, the sound will come from the TV. Even when I use msn to talk, the sound will come from the TV. But when I play a RMVB file with Realplayer, there is no sound from the TV, but from the computer. Does anyone know how I can make the Realplayer sound go to the TV?

thank you!