This is a guide showing how to stream media from your PC to your Xbox 360.
First off make sure to place your media files into the appropriate folders. Either My Videos, My Music, or My Pictures. These folders can be found in My Documents.
After you have moved your media into the correct folders make sure you have the latest version of Windows Media Player.
You can find the latest version here.
After you have installed it start WMP.
Once it is running select Library then click on Media Sharing.
Check the 'Share my media to:' box then click ok.
A new box should pop up. Select your 360 and click allow then ok.
After you have done that you are now all done with WMP and should now be able to stream media from your PC to your 360 with ease.