This can only ever be a preliminary opinion, of course... The answer is it depends on your business.
Unless you have the very latest hardware, the chances are that Linux will install perfectly on your kit. Linux is just as stable as Windows and vice versa, so much so that no one talks about Operating Systems crashing anymore. In terms of basic business applications, OpenOffice provides all the word processing and spreadsheet functionality that most users will ever need - although it doesn't look at good as Microsoft Office. So why wouldn't you install Linux?
If I look around my own business I can't see anyone who just needs basic OS and Office functionality. OK, we are Windows software developers, so our developers need to be running Visual Studio - which only runs on Windows. But then, the people in accounts use an accounts package - which only runs on Windows... and so it goes on. Unless you are starting your business from scratch, you will have already made a big investment in Windows software. If you are going to move your desktops to Linux, you are going to have to move your applications to Linux as well.
What if you start slowly? Just move one group of users at a time? If you do that, you have interoperability problems. Using Exchange? Forget it. Evolution just isn't up to the job as an Exchange client. That means making a strategic decision in advance to move key functionality to cross-platform software. In the case of mail, that would be something like Lotus Notes.
On top of application issues you have people issues. You will need to retrain your IT staff and your end users.
So why bother? Why would you want to take on that much pain? You wouldn't; of course you wouldn't. But perhaps your business is already running Lotus Notes, perhaps your business is using browser based applications, or Java applications; perhaps you only have a handful of Windows only programs. In that case, why not?
I can't help thinking however, that to use Linux as a business tool you have to lock it down. The real power of Linux lies in the fact that - unlike Windows - it isn't locked down. That's not a reason not to use it as your business desktop, of course. It's just that there may be better uses for Linux.