schmea: As for how reliable they are? I probably wouldn't risk it. Even if the modder is trustworthy, and I do believe he is, his website or his host could have been hacked at some point. I'll email Greyfiend and let him know, in the hopes he has no idea and can clean it up. I'll also remove the link until further notice. Thank you for letting me know.
I'm really sorry for recommending something that turned out to potentially have a virus. It's an incredible shame, since I've had so much fun with his mod over the years!
Psyringe: I think it's more likely to be a false positive - mods sometimes do things that are similar to the behavior of viruses. But if you could ask the modder, that would be great!
The link that triock posted
here might be useful. It shows which antivirus programs see which kind of threat in the file.
I sent him an email with Triock's link. Hopefully the file is safe, but better to let him know I think. It really is an incredible mod... makes the game a truer homage to the original XCom than the actual reboot, in my opinion.