Not wanting to go down the RGB cable route for the best picture (no spare RGB slots, and I don’t want a switcher), I decided to buy a cheap blaze s-video cable off ebay from hong kong. The cable arrived quickly (took 7 days from auction finish to arrive), I plugged it in and switched my tv to s-video mode and turned everything on. The tv gave an unstable picture, as though it can’t find the sync (a bit like trying to sync an old cablecrypt cable signal). So I tried setting 480i 60Hz mode on the wii and it still didn’t work.
So I tried plugging in the composite connection that comes with the blaze cable thinking the cable could be faulty, but it worked perfectly fine just like the composite cable that came with the wii. I then tried both the s-video cable and the composite cable at the same time and I got a picture, but not in s-video mode. However the picture is a clearer, brighter picture than the composite cable on its own (I tested it by pulling the s-video cable out), so it does work although it’s not a proper s-video picture.
Reading around the Internet it appears s-video doesn’t work with PAL wii’s which is annoying, why did Nintendo do this, surely the pin-outs would be the same on all consoles. Anyway my advice is to try use component if available on your tv, then rgb, then s-video if your tv can take s-video and composite at the same time into the same port (you can get scart adaptors that allow this if you have scart) for a better picture.