Yeah, I'd pass on NoScript too. As for Linux, it's irrelevant - it needs to be something the OP is familiar with, which likely means Windows. Not to mention, learning to use Windows is much more useful in later life than learning to use Linux, unfortunately.
That said, Linux isn't too bad once you've got it all set up - which can indeed be a pain in the arse due to driver issues, or different releases, even of the same distribution, changing completely at random (I remember I used to use Ubuntu. Then more recently I installed one of the newer versions, only to discover that half the audio software I'd used before no longer worked out of the box because they'd suddenly decided to replace ALSA (which was the entire audio backend) with PulseAudio, which is totally different, and hadn't provided any kind of legacy compatibility).
Once you've set it up, Linux is great for everyday stuff - web browsing, email, music, watching the occasional video (less good for office work, since OpenOffice is a pile of crap, but there is some decent word processing software out there). So for a seven year old, it would probably be absolutely fine. My grandma uses Linux quite happily (her Windows 98 laptop broke a couple of years ago, so she was forced to upgrade), with no problems at all, for example. Linux only becomes difficult if you want to do something more complicated, since that either requires some configuration, or a Windows application - which are frequently difficult to run in Wine, and the Linux equivalents are often nowhere near as good. Photoshop vs. Gimp, for example.
For a 7 year old, once it's got going, Linux would probably be fine. But it's irrelevant, since the OP would probably prefer not to have to make the effort of setting it up, and trying to fix it in the event any troubleshooting were necessary.