Well maybe it may be due to the fact that 99% of all corporate IT projects use Microsoft software on generic PC hardware ?
Which itself is due to the fact that a whole generation of managers have made IT project decisions based on the Intel-MS platform ?
Or can you list a hundred consulting companies that have Linux specialists on call for IT projects ?
I doubt it.
And as long as this situation does not change, the default platform for viruses will remain Windows, because the vast majority of users, including the clueless ones, are using that because it's what they have available.
You can have as much security as you want, as many confirmation dialog boxes as you wish, there will always be a moron somewhere who will decide that Yes, he absolutely wants to run this AV-flagged virus-ridden trojan package NOW because either he knows what he's doing and has a malicious intent, or he's a Darwin Award candidate and just HAS to see those pics of <insert celebrity slut of the day> in the buff on his corporate PC.

How is it that every time a virus pops up, Microsoft products get bashed? I understand that Microsoft products are at a higher risk because they are the more prevelant and targeted systems on the market, but good POLICY and a good network security setup should protect a network better than anything else. just because you run OSX or *Nix does NOT make one invulnurable to attack, no matter how much brainwashing has been done.
Also please note I used ATTACK and not VIRUS. no system is completely secure unless it is located in a bomb shelter 2 miles below the surface with no connection to the outside world, the passage filled in with concrete and it is never turned on. sorry Deimios, but your uneducated attack on microsuck deserves a FAIL. but yes, their SysAdmin needs to be fired for that one...

Its Criminal What People Do To Deny wrongdoing, & heres Perfect example. Although Felony To Lose Medical Records or Alter them, When Theres Conflict, Records Go In Trash. No Nothing.

Physician Thomas Stewart von Drashek M.D. Would Never Alter or Delay Your Prescription. http://www.geocities.com/tsvondrashekmd/THOMASSTEWART.html

I don't actually remember name of first patient Not Last Nor Any of EM, Yet I'm Clear in Deep, Dep Green.
Signed:physician caregiver thomas stewart von drashek m.d.

They were probably using Microsoft products.
The problem here is not that they caught a virus, it's the mere fact that a HOSPITAL of all places is susceptible to computer viruses.
As medical equipment becomes more and more integrated and networked, even if the equipment OS itself is secure, the controlling computer can be infected with potentially lethal results. If a life is on the line, a Blue Screen of Death is not something you can afford to experience.
They should fire their system administrator on the spot.