Actually, less and less by the day. 10 years ago I'd agree 100% with your statement. That's changing daily. As more and more applications move to the cloud, and become even more Web-centric, the need for a PC, or more specifically a "Windows" PC will be moot. That's why OS X Lion, and soon Windows 8, are moving toward their respective mobile siblings, in terms of look/feel/functionality.
Within 2 - 3 years, Windows, and yes even OS X, systems will be the exception, not the rule in business. That isn't to say they'll be completely eradicated; far from it. However, the trend is starting. Larger company's rarely issues "PC's" any more. They give new staff a stipend, and let them get what they want. The users then connect to a Citrix, or VDI environment for applications, or directly to the web.
Server admins, etc. will still be needed, and they'll definitely need "Windows" skills. However, they'll be more suited to get a good working knowledge of security, Web Servers, and understand thin provisioning [ala VMWare, etc.]. Those with MCSE's can use them for wallpaper