When choosing an S-video lead you need to check if your adapter is 4 or 7 pin.
Most 7 pin adapters do work with 4 pin as the pin allignment is the same however there are some that dont so it is best to check your Graphics card/Tv Card/ Analogue converter manuals.
Check that the lead is two directional or works in the direction that you need it for. I.e. Some PC to TV leads wont work as TV to PC,