Mac, Linux skills grab higher salaries than Windows
news.cnet.com
news.cnet.com
Then, as we move into the real IT jobs, the word "Windows" probably doesn't show up, since it's assumed that you already know it. (I forgot to ask "what OS do I have to use" at my first job interview, and ended up having to use Windows without having any Windows experience. Fortunately, VMWare made that problem go away.)
If you're a student hoping to get a job after graduation, your best bet is likely to aim for the largest and/or most resilient markets.
No, please don't do this. Focus on something that you really like, and get really good at it. Then you will always have work, regardless of the market's whims. (If you took this advice 4 years ago, you'd just now be ready for a lucrative career securitizing mortgages. Have fun working at McDonalds...)
Here in the UK, developers using Microsoft technologies are easily paid double what your average LAMP developer earns (in my experience).
However, back when I was looking for a job a couple of years ago, I interviewed for ASP positions - same hours, same benefits, same location, etc - that paid twice what was being offered to PHP developers. If I hadn't been so much more experienced in PHP I definitely would have gone the Microsoft route.
I keep an eye on the local job market (every few months) and this doesn't seem to have changed. Be interested to hear if it's the same by you? (Are you UK based? I can't think why I've got that in my head...)
Surprised?
Maybe anyone who can afford to fill their office with Macs can also afford to pay top dollar for engineers to program and maintain them.