How do you create a media library and to back up and play directly on my tv without using my computer to play them creating my own media on demand?

How do you create a media library and to back up and play directly on my tv without using my computer to play them creating my own media on demand?
Many ways to do this.
One way (the way i am doing it) is connecting a WDTV Live to my TV. WDTV Live can connect to my network harddisk (or a simple USB, external harddrive) where i have stored all my moviefiles, music and pictures. Chances are you already have an external harddrive of some sort. So i think WDTV/WDTV Live is a cheap option.