You never learn if you never take a risk. Just back up what you can. It's your machine after all!!(just don't practice while accessing my online banking please)
I wholeheartedly agree! Most of what I know has been self-taught, but my words of warning were strictly for the newbies & inexperienced. If they screw up their registries it's highly doubtful they are going to have the skill to fix it. Which means annoying a friend to beg them to come over to fix it or it's a trip to the repair shop and a costly repair bill.
Advice to the inexperienced regarding the registry: Always research first what you are thinking about changing. Don't always assume the change you are about to make that seems logical always is.