I've been a Windows and *nix users for over 20 years. Back in January I decided to finally start using Macs as I'd always had this image in mind of sleek, stable, intuitive machines that had but one drawback: price. Sort of like Mercedes Benz.
Well after a total of four Macs (an Air, a MB Pro, and two Minis) used intensively daily in a mixed environment with some Win7 and Ubuntu machines, I can say without doubt that Macs (OSX) are certainly no more stable than a $399 Walmart Win7 PC, and since Lion they are definitely FAR less stable than even our worst Windows machine. It's like finding out the lingerie model you miraculously began dating is a closet schizophrenic -- very disenchanting to say the least. I've lost work several times on Macs, something that has not happened to me on Windows in quite a few years. All of the machines have frozen solid at one time or another, requiring a hard restart. Apps freeze regularly, and the overall experience has led me to not trust any of the Apple machines for serious work unless I compulsively hit Command-S every 10 seconds or so.
All of the Apple fanboy talk about Windows crashing all the time is pure psychological projection. They unconsciously project the instability they encounter in their Macs on to Windows machines, and then multiply it by 10 for good measure. In reality a healthy Windows machine rarely ever crashes, while Macs do it almost daily.
Windows does of course have far more malware problems, however that tends to affect mainly people who are clueless about computers. I haven't had a malware problem in Windows in years by simply practicing "safe computing".
All that said, there are so many dead sexy aspects to these Apple machines that I am absolutely torn. Despite the fact that it simply lost several hours of work back in March, I remain in love with the Mac Air.
Bottom line: if Macs really were as reliable as the fanboys pretend they are, Apple would absolutely rule the computer world. As it stands, be prepared for a great deal of disillusionment if you "switch". The fanboys are doing Apple no favours by fabricating myths.