You don't need to install a new OS, you just enter a Windows Pro license key to upgrade the version? Buy the key online, send it to your parents, tell them where to enter it, done.
Also I don't think your parents want to use that particular sandbox. There's no persistence at all: no bookmarks, no cookies, no history, no local documents, ...
The no persistence is why I like it. It would be ideal if I could ask my parents to do their entire browsing in an ephemeral sandbox and even if they end up clicking / installing something from a shady link it wont blow away their (real) persistent OS install.
Also I don't think your parents want to use that particular sandbox. There's no persistence at all: no bookmarks, no cookies, no history, no local documents, ...