this is just one solution i found for connecting a xbox 360 to a linkstation without having a pc on all the time. i have a LS-WTGL/R1.
setup a windows media center edition pc (how you to do that is not listed here. try google), and connect to any shares on the linkstation.
connect the xbox up to the media center edition and go into any of the media options and add the linkstation share. it'll start to poll for any media on the drive, but you don't have to wait for that to finish.
exit out of media center extender, and shut down the media center machine.
go to picture, video, or music library on the xbox. the linkstation should now show up as a valid pc. before you select it as an option, though, you have to login to the web interface for your linkstation. go to media server, and the xbox is now listed as a valid dlna client. select which share contains your media files, and click apply at the bottom of the page. on the xbox, you should now be able to browse through videos, music and pictures on the linkstation.
note: since you are only allowed to select one folder as your media server share, you must have all your music, video and pictures in that share.
i've repeated this with my xbox and linkstation 3 times, and it is working on my friend's linkstation and xbox as well. these same steps don't seem to work using windows media player or zune software. the pc always needs to be on for those, it seems.
good luck