[SOLVED] Totally lost! help!! KDL40NX803

I'm here after whingeing on the Sony forum about the "pickyness" of this TV when attempting to play video from my PC.
It will only play Mpeg 2 files, and even then, it rejects some and plays others all converted with the same software!
I've minutely examined each file's "properties" and can find no differences!
"Catmambo" from Sony recommended this software which I've downloaded but before I install it, can someone explain a few things to me?
Does it alter my existing file system or create it's own?
I've seen lots of "code" on this forum....do I really need to "get down and dirty" with it?

Does the fact that my model doesn't feature in your list bode ill for me?
Please keep it simple!....I've managed to master most things on computers but video, codecs, containers etc is something of a black art to me!

Just re-reading the list of 2010 models, they are using firmware ver. PKG4.099EUL-0108, mine is ever so slightly different... :- ver. PKG4.099EUH-0108
just thought it might be helpful!
