still depends on required tools
A GUI is a GUI these days. Someone who clicks around an IT department provided Windows workstation really has no excuse and will pointy-clicky around any other GUI icon'd desktop as easily given a day to become familiar with it. A good IT department can make the worker's experience painless.
It still comes down to required tools though. If someone is using the 5% of Photoshop that is not replaceable then they require a Windows platform and Photoshop. If AutoCAD is the only thing that is going to work for your drafting and CAD/CAM staff then it's a Windows platform. If it's the 5% of Excel that OOo still can't support or legacy MS Office only homebrew apps then your locked to Windows still. If your network admin needs to test Windows authentication and protocols then they will also need a win32 VM or boot partition.
Office managers and other staff who use general purpose applications have no excuses and "but I have this template in Word that I can't live without" doesn't cut it.
There are still possitions where the job dictates the applicable platform through the required applications. In terms of general computing use though, it's more about the IT department providing a workstation rather than about the end user learning it.
'but I don't want to learn something new' - well, at home you don't have too but here at work.. this is the tools that we provide for your job. Is there something specific you are unable to accomplish because of it?
