I don't if you what media server in a ps3 is...errm...where you can watch the files you have in your PC in your PS3, you need both of these turned on...
You need a rooter and internet, I think.
You can use your windows media player for it, but there is one problem...it can't read all files, not even subtitles files...
However good thing, there is a excellent software for this, it can read all files (including subtitle files), images, music files, etc, even disc data driver from your PC can read (example: "DVD RW Drive (E:) Varios"), pretty neat, huh?
Click Here to Download PS3 Media Server
Here is a tutorial:
It's quite simple, isn't it?
but don't forget, the PS3 Media Server has to be on and connected to your ps3 to work everytime you use your ps3 to watch videos, images leisten to music in your PS3 from your PC!!