You could use Logitech stuff (squeezebox), but Sonos works a good sight better (better bitrates, seperate WI-FI channel so it doesn't clog your router, synchronised tunes across all rooms).
It's worth it for sure. Depending which kit you go for though, you can plug into meaty seperates.
An S5's and Play systems are great for wandering speaker kits (kitchen, then garden, hell, even the garage) but a fixed unit (a zoneplayer 90 for ewample) is always good to have attached to your main stereo system.