I always figured MS would know the most vulnerable areas of their OS.
Not sure why they would know anything about Mac virus', however. Much less how to remove them or even access the innards of the file system.
On the other hand, they might have a great list of threats and how they would be coded.
Two AV rules:
1. I don't pay for any AV software except ClamXav.
2. I don't install anything made by MS.
Rule 1 takes care of finding any Mac malware.
Rule 2 takes care of installing opportunities for malware in my computer.
I use SpamSieve to help control Phishing, which is a lot more to do with logical thinking than following coded rules.
As for "cloud storage", that's just some elses computer and hard drive. We have no control over how well they protect our files. I used to fly through clouds for a living. They are extremely flimsy! I'm waiting for Sea Storage. Do you realize how much pressure 100 feet of water creates?! Folks will have to build super-strong subs to try and mess with anything stored at ~20,000 leagues!
Your milage may vary.