I don't know about the UK, but I can tell you that nobody in Germany uses Macs in a business environment, and I've only seen three Mac users - take that number literally - while I was still working for the United Nations. It's actually easier to find people with Ubuntu Linux on their machines than it is to find Mac users.
But it's interesting that you seem to experience the very same compatibility problems that I had with an Apple notebook in every office so far. You usually can connect to the company network and get Internet access, but that's where the story ends. Office documents lose their formatting, Office makros don't work, file server browsing might still be possible, but you cannot expect it, but usually none of the large office printers has Mac drivers - or if they have Mac drivers, which is extraordinarily rare, they still won't work with Intel Macs and only support Mac OS X Jaguar or Panther. (Konica Minolta, anyone? And Sharp only has pay-for Mac drivers which, of course, no company buys.)
And here is where owning a Mac really pisses me off: Ubuntu 9.10 does not show ANY of these problems in my company's office. Snow Leopard couldn't even print, but Ubuntu could do it out of the box. File server browsing also worked out of the box with Ubuntu, Snow Leopard didn't even find the Windows shares.
Since Windows and Linux are the platforms where I make my living, I today decided to finally dump Mac OS X. I've put the expensive Apple software on eBay two hours ago and made Windows 7 the only operating system on my Mac Pro. And there are only two reasons why it is Windows 7 and not a flavor of Linux: My USB scanner is not compatible with SANE and I do not believe in emulation layers to play games like Civilization IV, STALKER or Half-Life.
The killer arguments for Windows are: I no longer have to turn on my company notebook to work from home. All the software that I need also runs on my own desktop machine. And that is very handy when I'm on 24/7 duty.
For me, this is now the final Goodbye to the Apple world. My Mac Pro is a good machine, although too loud for my taste. I'll keep using it until I need a new computer, and when that day comes it will be one of those completely noiseless PCs. A Quad Core with 0 db(A)/0 Sone. Probably one from SilentMaxx.
OS X is a nice platform for certain purposes, but it has many restrictions and a devilish vendor lock-in. It took me five years to figure out that Windows is the lesser of the two evils and to accept defeat.
Maybe Windows 7 will only be an interim-step on the way to a full migration to Open Source platforms. But that depends on a couple of other factors. I would love to completely dump commercial (application) software and be free from vendor dependencies and also be free from being their cash cow.
Well. Let's see how things develop. I have not yet given up on Linux and FreeBSD.