Well, in many ways, Linux *is* inferior to Windows. Don't kid yourself. Especially for business use.
The fact is, most business software is Windows only. That's the deal-breaker for Linux, right there.
And Linux has nothing to compare to Active Directory. If you have to manage a bunch of desktops, Active Directory and Group Policy have no real equivalent on Linux. Yes, there is Puppet and stuff like that. But it's a colossal pain-in-the-ass compared to the very nice GUI tools (and Powershell, now) that Microsoft provides.
Linux has lots of advantages, but manageability isn't one of them. It lags FAR behind Windows on that front.
It's great for web servers and SMTP servers. Those are the only areas where Linux clearly beats all flavors of Windows, in my opinion. On the desktop...not so much. Works great for people that just want to use a browser and OpenOffice, though.