It does. There's constant fretting over Windows servers doing down, while the Sun, HP and IBM UNIX servers just keep humming for years.
I think the reason Windows has so much presence in the servers is because of cost-cutting measures back when UNIX was far more expensive than Windows. The government wanted to save money, so it started migrating from UNIX. What the government didn't realize was that what it was saving in purchase price it was losing in extra personnel hours, down time and complexity (several cheaper boxes to do the job of one solid expensive one). Do you realize what a headache it is to run Exchange to provide email for 20,000 people? It's frickin' insane!
I'm not saying unix is a bad OS. But to say they are fretting of windows is silly. You have to compare how the windows machine is maintained and managed vs. the unix system. The unix systems tend to have knowledgeable IT guys making 6 figures running them. Windows has 1 6 figures guy managing a bunch of guys in the 50-80K range. You don't get to touch the unix system til your certified but windows they throw the keys at you.
Plus a lot of windows servers are kept at people's desk and have no UPS or AV protection. Sure cost has a big part to play in it, but it's not as much the hardware costs but the operations costs.
No it's not. I've supported well over that number. The key is you have to buy the right hardware up front. Then Exchange runs like a champ. But it also requires a sound AD implementation.