Robbon44 - These days home-user PC Linux is very easy to use - there are free programs for the 2-4 year-olds - simple games, Tux click-colour, so on - so most older kids or adults shouldn't have any problems doing their everyday things.
The Distro (version of Linux) I've used for the last 6+ years, is particularly easy to use. If you can find your programs, internet, mails, so on - in the Win2k or XP 'classic mode' Menus - you'd be quite at home on this PC.
All Linux Distros install with a lot of ready-to-go programs already included - if your internet is connected to your PC, modem turned on - you're on internet in a few clicks. Easier than with XP. (Can't compare with later Windows I haven't used.)
Almost all Distros have good user Forums - the PCLOS (PCLinuxOS) I use has a particularly good one - which is very welcoming to New Users.
As for programs - all Distros have an easy-install mode from their Repos (repositories) - and this one uses Synaptic installer/uninstaller with which it is a few clicks to install multiple selections at once (no reboot needed) - to try out... The ones you don't like - just reverse the process... With now over 13,000 programs, tools, utilities, games, etc, in the current PCLOS Repo - it's often a "which suits me best" from several, choice, rather can "can I find something to do this...?"
As for running Windows (or other Linux Distros) inside Linux - quite easy - using Oracle's free (for non-commercial) Virtual-Box. I run Win2k-SP4 and an old non-activation 'Corporate' XP double-updated to SP3 - which opens in 3-clicks to a fully running XP in 7-8 seconds. I've allocated it 1GB RAM to run on, and 256MB Graphics - so it's pretty lively....! See pic - I changed it from fullscreen so you can see it's in Linux. The bottom icon in MyComp is the directory in Linux used for transferring items between the systems. Internet - I.E. or Firefox - works very well from XP, there.