Originally Posted by UnseenMenace

If its a Windows OEM or Windows home as stated you will not be able to install it due to Windows Genuine Advantage (WGA) which is an anti-piracy system enacted by Microsoft that enforces Microsoft Windows online validation of the authenticity of several recent Microsoft operating systems...... Which means soon as your sister puts the laptop online Microsoft will shut it down

Not that it can't be got around apparently

I got around the WGA on my laptop by installing Linux