For kids, all they want is the best stuff available across all operating systems. They don't wait for the machine to reboot from another partition or from a LiveCD. Besides, while they can switch between applications easily, restarting a different OS is bit much to ask :-) [although I won't be surprised if they do that!]. Kids want to switch between interesting applications/games/edutainment stuff rather quickly. Also, we don't seem to get all the good stuff on the same OS! For example, I need to Scratch on Windows or Mac -- no official Linux binary yet :-( While it is possible to hack to run Scratch on Linux by taking the Squeak image, there are issues with MIDI etc. There are many good stuff in Edubuntu and OLPC too. The point is that you want to run the best set of applications/games across operating systems -- without having to reboot.
This is where Virtualization helps! As Tim Marland said, you don't have to be a hypervisor/virtualization expert to use it. I downloaded VirtualBox for Windows XP [just run .msi file to install] and edubuntu [this later was very easy -- I just to use Add/Remove programs menu and look for "VirtualBox". VirtualBox is very easy to configure -- mostly point-n-click stuff. Now, I can run OLPC, Edubuntu and Belenix on my Windows XP latop without having to partition my hard-disk or rebooting. Kids can switch between their favorite applications across Operating Systems easily. If you are curious how it looks, here are some screen-shots: