Music systems for multi room listening

[The Tom Bomb]

I don't know if this falls under htpc, but it's probably the closest. My parents house is pre-wired for sound in four rooms. Each room has a dead panel with cat5e and two sets of speaker cables. The cat5e from each room goes to one panel in the tv room. I really have no idea what kind of system I should be looking for or what I should even be googling to find out. Any help would be greatly appreciated.