Thanks guys

My operating system is max os x (G5 mac)

Sorry should have said...

I have downloaded vlc thanks and if I drag the download into vlc on the dock it works!
but I only get a little picture and if I open to full screen it is very fuzzy and bad quality. Is there anything else i can do now to get better picture on full screen?
I cant see the point watching a movie on tiny little screen, can you help here or is this the end result?