I've ordered a new hard drive to replace the useless article that I couldn't cajole into action yesterday. Let's hope the new one shows more signs of life. I hope it's not just a case of some obscure incompatibility between the drive and the motherboard, because I've ordered the exact same model of drive again.
I've also ordered a new TV tuner card to replace the broken one I had to send back.
The package has already been despatched, so I may be able to report more as early as tomorrow. Until then, I'm keeping my fingers crossed that the new hard drive will actually spin up.