Instructions
Turn on your PlayStation 3. You'll need to have the PlayStation on for Windows Media Player to detect it as a device to stream on.
Open Windows Media Player. Click the Library button and choose Media Sharing. Select "Share Media to." Below the check box you'll see a list of devices to share your media on. The PlayStation 3 will show up as an unknown device.
Select the device, and click the "Allow" button.
Check your PlayStation 3 under Photo, Music or Video for your media server, which should show your computer name. If the media server isn't present, choose "Search for Media Servers" under any of these menus. This will detect media servers running on your network.
Select your media server. There will be four folders: Music, Video, Pictures and Playlist. Choose the folder appropriate to the section you're using. You can only stream videos from under Video, music from Music and pictures from Photo.