Yes, a windows 7 server absolutely could be setup to be secure, even if it was the main computer you used. But now let's be really honest, if someone is asking about setting up a node on their win 7 desktop, do you really think they are capable of doing that? Absolutely not.

There security implications go so much further beyond just getting hacked, by hosting your node on a residential connection and not in a data center, a nefariousness person could find you. Social engineering is a very real thing and works much better than hacking. So now, the hacker has your home address and location of the server. Fuck trying to hack you, they'll just drive to your house and rob you. Or, park out front, grab your wifi key, send it to a cloud GPU cluster to crack it, then because 9x.xx% of people don't change their router password (not wifi, the root router password) from the defaults, they could change your DNS servers to their own DNS servers and monitor your traffic. Then, when you went to an unencrypted site to download something, they would MITM attack you, directing you to their own server and feeding you a fake download link with a RAT. There are plenty of RATS which go 100% undetected, so your antivirus will do nothing. And you won't be the least be suspicious because the file you are downloading is from a trusted site. Or so you thought.

And the thing of it is? If you spent $5 / month on a VPS and just ran your MN on a locked down linux server in a secure data center as recommended, none of that could have happened!