Let me just add, its not the speed of the Wifi as I can stream the same video to any of the laptops in the house without any problems, its only on the n900, and I seem to think its something to do with codecs, but I have installed the extra codec pack so maybe not?

Is there anyway terminal command to check to see what codecs are installed, and what codec the file i'm trying to play is? Maybe that would give me something to go off?