So I think the parts are OK, they just have a little urine on them. How do I clean these parts?
A bit got onto my power supply as well. I am not keen to open that thing and try to clean it. Should I just trash it for safety reasons?
The rubbing alcohol will dry sooner. You should try to do this in your garage or a very well vented area, if possible.
Conveniently, rubbing alcohol will also neutralize most smells from urine.
I'd trash the power supply, since a short can damage other more expensive components. I'd clean the case and case fans with warm water and lint-free paper towel then let them air dry thoroughly.
Furthermore, I'd wait for any circuit boards to dry completely from urine, try to blow off as much urine residue as possible with air pressure (e.g., Disposable Gas Duster), then try to dry-rub as much of the remaining with high quality shop towel and Q-Tips. You can use a tiny amount of distilled water on the towel to increase transfer, but less is more (talking droplets, or the stuff from your breath, not saturated).
If you run it while wet, it may fry things, if you run it after it dries it is more likely to just smell really terrible for a while.
>My Toddler Micturated on My PC...
That's a bit of a pisser.