mattjax05:bigboss:There is no way to have the wireless of the ZonePlayer/ZoneBridge communicate with the wireless of your router, so there has to be a bridge of some sort, whether it is the ZoneBridge/ZonePlayer, a 3rd party bridge, or something like the Ethernet over Power devices.
If the Sonos doesn't communicate with your router's wi-fi, it cannot access the songs on your PC / NAS drive.
Ok so I now know you need the router for access to music - but how do the players make that initial link to each other and communicate from thereon, is it via the router?
Right, Sonos uses its own wireless mesh network for communication between Sonos devices, however they still need to access your own network to a) access the internet and b) as bigboss said, to access any stored music you have on your own network, therefore they must have IP addresses that relate to your home network. The usual setup is that one Sonos device must be wired to the router, this provides the physical connection to your network (it IS possible to do this wirelessly in fact, however it's not a configuration supported by Sonos so I've never tried it and may well lead to bandwidth issues), it is through this wired connection that the rest of your Sonos devices will acquire their own IP addresses and all data (ie music or firmware updates) will pass through this wired connection.
Each Sonos device acts as bridge or extension to your own network, any device you connect to the network ports on the Zoneplayers will be able to acquire an IP address from your router (Sonos devices do not have DHCP built in, hence the requirement to get IP addresses from the router), so you could connect your NAS to one of the Zoneplayers if it's more convenient. In fact it IS possible to do away with the router, if you have a PC that has DHCP running on it and can route connections to your external internet connection (if you had a mobile dongle or basic ADSL modem for example), you could connect one Sonos device directly to the PC and then the others could connect wirelessly and you could plug other devices (such as a NAS or even printer) into the Zoneplayers to allow them to access the PC. In reality all you've done here is swap a hardware router for a software one running on the PC.