I think I would introduce the CPU before the motherboard, then when talking about the motherboard, use a sentence such as "If you think of the CPU as the 'brains' of the computer, consider the motherboard like the central nervous system.". Just seems to flow better.
Then perhaps later "Keeping with our human analogies, this part would be like blah blah"
At this point I'm just nitpicking sentence fluidity though.
Fact-wise it all looks good.
If somebody tries to correct you, don't lose your composure, if you know right off the bat that they are right just flow with it "ah that's a good point blah blah blah" or if you're unsure, say something like "according to my knowledge/research, blah blah, but it could be possible that blah blah".
It's a public speaking class, not Computer Technology 101; I'm sure you'll be more graded on your presentation and composure than having up-to-date, solid accurate facts. The teacher probably won't know the difference anyway.