How can I rescue my data from a dead PC?

Linda's old Windows XP system died, and she'd like to retrieve the data from the hard drive and transfer it to her new Mac

I have read with interest your article regarding the disposal of old PCs. I have a defunct Dell running Windows XP, which crashed out before I had a chance to retrieve any data. I am now wondering about safe disposal of the old PC and whether or not I can transfer any data to my Mac. I am not a technophile and this may be a silly question, but can you tell me where the hard drive is located? How can I access it, and should I keep this in a safe place even if I can no longer use it? Linda

I wrote a comprehensive answer to How can I safely recycle my old PCs? almost a year ago, but it's still a question that comes up often. For example, Kris has just asked a similar question, saying: "I seriously do not even know where a hard drive is located, let alone how to remove it." The motherboard in Janice's PC has failed so she wants to know if she can get access to her data, and wonders if "the only option is to take a sledge hammer to the hard drive and commit it to landfill". And so on.