Ok - so my conclusion is that unless you are running a standard Raspbian distro, you can't get the TP Link W725N to work - as will be the case if you need to recompile the Kernel or use a custom kernel to get the Xin-mo to work.
So I shelled out €10 and got an Edimax EW-7811UN. Plugged it in, rebooted and hey presto - PiPlay shows my IP address - couldn't have been any easier!
woo! sorry you had to shell out some money to get it working. But hey, at least it works! I was just reading that the latest linux kernel now supports arm 7 (raspberry pi 2). That's good news for everyone because we will have more access to stable drivers!
I'm really happy with the performance of my setup with the Pi 2. I was using a PI 1B and sound was very choppy on SF2 but now it's perfect! Very pleased