So the way I see it the best way to explain the workings of a computer is to paint a happy little face on it and make it dance around and basically anthropomorphize it and say what each component corresponds to in humans. But I don't feel like drawing so I'll just make a list:
Motherboard: Your nervous system; the thing that sends all the info back and forth. Your other components are compatible with it so they can send the right amount of data. If you got a wrong component you could short circuit it and then you're fucked.
Hard disk: Long term memory. This is stuff you'll always know like trivia or who the Terminator was played by or months.
Memory: Short term stuff. Like if you were knocked out you'd probably forget about it. Or if you went to sleep. You know. Like "oh I have to go do my laundry" and then a few hours later you forget that you were supposed to do it and then you're like oh shit.
Processor: It's like your IQ. The better processor you have the faster you can figure out logical stuff or math and things. If you've got a slow processor you can still do most stuff but it'd just take you a little longer to find out how.
Heatsink: While we don't have fans we do have pores to let out all the heat generated by our stuff. And most of our heat comes out of our head, and that's where our processor is. You dig?
Video Card: Your creative ability; your talents. A lot of the time people mistake it for your actual intelligence but that's whack. It's like, if you have a good graphics card you can draw pictures really good or think up of really good designs or build things.
Sound Card: Stuff like pitch and the ability to speak whatever languages you speak. Not too important.
Power Supply: Your metabolism; your ability to get power from your input and put it to use. You can get by with a low watt power supply but make sure you don't overwork yourself.
Case: Really unimportant! Who cares what the hell it looks like! Just make sure it's big enough to house all your stuff and you can do whatever you want to it. Tattoo it, you know. Just don't bang it up too much because you gotta protect the stuff inside.
Chipset: Your consciousness. No one really notices any difference at all but that's because they're the only ones aware that they gots it.
Monitor, Speakers, Microphone, Keyboard, Mouse, That New Touch Sensitive Finger Reading Thing: Oh you know, that's easy. Sight, sound, hearing, touch, etc.
Disk Readers: Okay on this one I'm stumped. Not until the time of the Matrix will we be able to plug stuff into our brains to get stuff off of them. Computers: 1 Humans: 0
Network, USB, other connections: Sex!