Link pc to LCD TV?

i just bought new 40" 1080p Samsung LCD tv, and tried to link my gateway laptop to it. I used VGA cable, and i can see pretty much everything on tv. since i download some AVI movies, i am able to run it on my laptop through realplayer or wmp, but on TV, all i see is the player, but no movie running, only blank. how come? is it set up? everything else shown on tv.