Honestly, when installing any Windows, getting legit keys are very easy to get. I bet the laptop or PC your using has one on the sticker. If you want a newer version, go to some pawn shop and get a key from one of them.
If it gives you trouble, call Microsoft and go through the automated process for them to get it authorized. I have several keys I use and have used. It is a bad idea to torrent proprietary OS's anyway, not saying I haven't done it and that it's all bad, but for the most part bad shit happens.
But honestly, Linux is a WAY better alt to Windows and it's free. If your not the only user, then try and talk them into trying it. They will all throw a bitch fit anyway once Windows 8 is forced on them. I can almost bet average users only use it to serf the net and manage music and shit. If they are a heavy PC gamer, they would/should have a dedicated rig with legit shit on it anyway.