I posted a question recently about "how much do design jobs expect you to know?"
I have come across a couple recently that require you to use a PC. I only own and have worked on Mac computers, has anyone had to switch from a Mac to a PC or vice versa? I have applied to these jobs but know I would be quite slow at adapting at least to begin with.
They're very similar these days. And in fact, I prefer networking and windows explorer to OSX. Once you get used to hitting the Ctrl key instead of the Cmd key, you'll be right. And finding program settings will probably trip you up. But all pretty minor issues really.
I actually had some event company client ask me just yesterday, after they had commented "I presume you use a Mac" during a discussion about some work and I told them I didn't: "Why don't you use a Mac?", as if the tool was what matters...
What @Dave said. People are often shocked I don't use a Mac at home. Having the most basic knowledge in how a computer works has always lead to me being branded a "nerd", as if they're not a tool people have been using every day for the last ~20 years.
I've found that my PC crashes a lot less than the Macs I've visited in my freelancing travels. It's personal preference, and like @Kensmith said, the Ctrl / Cmd is the biggest issue you'll find.