M1B, that, too, is a good point I hadn't considered.
Although all components such as HDD, CD-ROM, FDD, Battery, PCMCIA socket and so on, are all "plug-ins", their sockets must be hard wired to something and I guess that will be the MoBo.
When I can prise it off my lad at Uni (probably Christmas now), I will do some investigative screwdrivering.
In the meantime, I'll go and look at the Tom's Hardware site. Any other ideas from anyone?