>I have a friend who owns a small residential seminar centre about 150 km from where I live. Her PC, which I set up for her more than five years ago, is used for the usual office-type tasks and is running Linux.
How about QuickBooks or TurboTax or something like it? Or maybe a couple of games?
> Please explain why it is impossible to get a modern Linux install to a point where »it won't be perfect, but it'll be good enough«.
Because it is. A lot of software is simply not available on Linux, a lot of hardware STILL doesn't work completely.
In my experience EACH company has at least a couple pieces of infrastructure that are not supported under Linux. From softphones with T.38 fax sending to high-end printers with Windows-only configuration utilities. Or maybe that nice order-tracking system with WinCE-based wireless scanners. Or maybe that small Access database that tracks lab samples. Etc.
Seriously, start a company and try to offer migration services. You'll quickly see that the RealWorld(tm) is quite a bit different from "just use OpenOffice instead of MS Office".
What can be done? First, you need to start from a "known good" situation. Chromebooks offer a nice opportunity here - they work just fine, have a nice management infrastructure and are explicitly designed NOT to replicate all desktop tasks. So using Chromebooks to augment existing Windows-based infrastructure should be quite easy (we haven't tried it yet, to be honest). Then this platform might become attractive to third-party developers, so it can be slowly expanded into more general 'desktop' usage.