Old computer plays both video and sound, but

I just bought a new Thinkpad T410 and transferred my old video documents on it. When I use the old computer (Dell Demension 2400, windows media player for windows 95?), it works fine and it plays both video and sound. But on new computer, it only plays sound.

Could you please tell me how to fix it? The video document were taken by logitech webcamera about 5 years ago.

Thanks a lot ahead of time!