setting up a dlna network

Ive been trying to setup a media centre kind of thing. Where I can access. All of music and video. I have it backed up on a hard drive and my laptop I tried using wmp and it didnt work I suspect cause I do not have broadband Internet. I tried to use an old router. As the network but it keeps cutting out. And reseting, Ideally I would just want a set top box that I could plug in a hard drive to and have it available to my computer tablet and ps3.