Using Windows Media Player as a media server
What do I need?
You need to be running Windows XP or Windows Vista with Windows Media Player version 11 installed. You can install Windows Media Player 11 free of charge through Windows update found here: http://windowsupdate.microsoft.com/
How do I start media sharing?
Open Windows Media Player and click the downward pointing arrow below the 'Library' tab, and then click 'Media Sharing'. In the Media Sharing dialog box select the 'Share my media' check box. You may be prompted to name your media server (give it a name that you will easily recognise), and that’s about it - media sharing is now turned on and you will see your media server listed on your Flow radio when you search for available media servers.
To allow you to play your media through your Flow radio you'll need to allow your radio to connect to it. Select your newly set up media server on your Flow radio and you’ll notice your media sever on your PC is alerting you to a new device attempting to connect to it (probably called an ‘Unknown Device’). Click 'Unknown Device’ and click ‘Allow’ to enable you to connect and play your media.
You'll now be able to stream your media from your PC to your Flow radio.
You can find out more about using Windows Media Player 11 as a media server from Microsoft: http://www.microsoft.com/windows/windowsmedia/player/faq/sharing.mspx