Open WMP11 and right-click on the Library Tab; a drop-down will appear and you need to select Media Sharing in order to open an option box. Now you can configure your sharing settings. Tick the “Share my media to” box and select your PS3, or “Unknown Device”. Click OK and it should be set-up.
You can now navigate to Photo, Music or Video on your PS3 screen and search until your PC shows up, where you can now easily access streaming content and other stuff through WMP11. You can also connect a USB drive or external drive if you wish, in order to access the content in it (i.e. if you have DivX or movies stored there). Simply plug the USB attachment to any of the USB ports in your PS3 and you should be good to go.