@Nick
Appreciate the information and will download teh software as you suggest but am skeptical about the end resuklt because there will be no unit for the software to link to thus it may/may not work (i.e. SONOS software is useless for any and all testing / use unless there is a device present)...
With Squeezebox there is a 'device' present as the squeezeplayer will act as a virtual clone of a squeeze player, just on your PC rather than a physical unit. As far as slimserver is concerned, squeezeplayer (assuming its the same as softsqueeze) will look and behave just like a real device. Quite different to the Sonos app which, as you say, needs to link to physically present devices.
I appreciate the pain with Sonos and wireless - when it works, it works so well that you use if for more than just listening to music. I am convinced that my house had lead lined walls at times as I use Sonos as a wireless bridge between my ISP router and my office network and once in a while the link goes down, reminding me that I am not on a fully wired network after all. I think the real problem for me is that I cannot get my ISP router central within the house, so external interference, possibly channels overlapping with stronger neighbours networks, or from a nearby airport which has the occasional military experiment going on, do not help when the signal strength lessons as I move away from my router and wired Sonos connection. Normally bouncing the wireless channel on Sonos a couple of times fixes the issue.