Finally went out and bought a piece of WiFi HiFi. Decided on the NetGear MP101 because it has the integral LED display so you don't have to switch the TV on to seee your music. Not too fussed about image and video viewing. And given that it'll be out of date anyway in a month or so you can't knock a price of £85.
A few hiccups during set-up - had to disable WEP, hard code an IP address and load the server software on my new XP machine rather than the Win98 "server" I had planned. But the delight at being able to sit back on the sofa, scroll through your whole music collection (400+ CDs and LPs) and play it on demand was just indescribeable. Well worth buying.