I think of non-Linux options as a joke. I would not even consider using BTC on a winxx or mac.
Plus Plus
I know too many people who are really smart who get some kind of malware at least once a year.
It's those damn browser plugins, they execute untrusted code on the local machine.
It's those damn advertising networks, the deliver malware in advertisements they don't check carefully enough.
It's those damn wordpress blogs, many of them have very poorly written plugins - and wordpress itself encourages the web server having write permission to files it executes.
Even though I have never had my Linux boxes infected with malware, I don't even use my main workstations for bitcoin.
I keep a small amount of my bitcoin in a web wallet - not more than I am willing to lose if the web wallet company goes all Mt. Gox on me.
The rest is either cold address or in Bitcoin-Qt running on a NUC with CentOS 7 that I just use to manage bitcoin.
I do use a browser on that machine to do things like pay bills with bitcoin, or log in to coinbase after making a purchase so I can paste an address to send the coins to. But I don't use that computer for anything else, so it has very little chance of malware getting on it.
But Windows? No way in hell would I trust it for bitcoin. As far as Mac OS X, I just don't like it.
Even if Windows is your preferred OS, I would suggest people get something like a NUC and stick a stable Linux distro on it for your wallet. Don't use the same computer you use for general Internet for Bitcoin, well, maybe a small amount is okay but not more than you are willing to lose for the convenience.