NoelDP said:
The ONLY trusted source of Windows Downloads is DigitalRiver.com
There are NO trusted torrents of Windows.
Good luck on your quest to educate this OP on this point. The OP does not want to rebuild the house, no matter how perilous a foundation it was built upon.

@OP - anti-virus, anti-rootkit, anti-malware software cannot find every infection; it is just not possible. Once a person has access to an operating system, they can add things that are difficult to detect. You say that the torrent was from a trusted source. Just keep in mind what kind of transactions/info you are trusting that source with - both offline and online.

Of course, we all trust Microsoft