The person should have an image(s) in case anything goes wrong and a working back up of all data. We all should have these anyway no matter what. The only way someone is going to learn is to try. But what really irks me is we are making the choice for the person based on our biases. To say "Don't do it!" is totally out of line. I say "either way is viable it is the persons choice". I specifically joined this forum to learn more about windows and haven't been disappointed. However versed we are in any oS is beside the point because we all were noobs at the beginning and had to learn in steps through trial and error. Don't deprive others of their learning curve. As one of my fav sayings goes "Rome wasn't built in a day". Rome started out with two people Romulus and Remus. Very unassuming and very lacking in anything. Eventually Rome ruled half the known world. Allow people to make their paths all the time being there to help. You know why I know a little about linux? Because I got my hands dirty and made plenty of mistakes. But the other ubuntu forum members were there to help me. That's how I learned.
Nothing is foolproof even virtualization. Someone will find a way to foul that up too or a weird error can occur. No software is immune from that.
P.S. I just want you to know this is in no way personal. I really like HTG. whs I have that pdf you posted on skydrive with all your video tutorials. I like most of them they are great. I just don't believe we should be steering people away from installing linux on a hard disk because we couldn't do it successfully. many, many people do it everyday and it is not hard as you say it is.
Aperson wanting to do this should really read about dual booting and GRUB before creating the Live CD/USB and attempting the install. Linux is not hard, it is just different than windows. The installation process is totally as far as you can get from a windows install. If someone expects linux to be like windows, then there is no need to install linux if they already have windows. Let the people decide which way to install. Then we will be there to help if needed. That's how they will learn, just as we learned.