Isolation when using dual boot

My son is of an age where he wants to use the computer but I don’t really want to just let him loose on the main PC as there’s lots of data on there that I don’t want him to mess with.

So this is my cunning plan. The machine has a spare drive and I intend to make the PC dual boot so that he can effectively have a new machine all to himself. Here’s the catch, I want to hide the other drives so that a) he can’t see, update, delete any of the data and b) if he ends up getting a virus or malware I’m safe in knowing my data is inaccessible.

I know I can hide the drives by removing their drive letter and have also toyed with setting the drives as offline in Disk Manager – question is will this give me the complete separation I want or would anything nasty be able to get access to my precious stuff?

I will off cause be running suitable AV and Firewall in the new instance and have everything super important backed up a number of times elsewhere….

Thanks in advance for any help

Instead of dual-booting, which is a dead technology in my eyes, why not just set him up with a limited user account. Then you can keep him from being able to do certain things or access certain areas of the drives.