The first cost is uncertainty. Its hard to measure uncertainty in any definitive way but that doesnt mean that it should be ignored. When you take a copy of Windows XP, Vista or Mac OS X and you install it onto a system with the appropriate system requirements, chances are that unless you have a particularly bizarre configuration or a defective component, you can be pretty certain that the OS will install and things that you have installed (WiFi adaptors, network cards, graphics cards and so on) will work just fine.
After all, youve paid someone to come up with a workable product where most of the kinks have been worked out (OK, I admit, both Leopard and Vista were released with too many kinks still lurking within the code). The same when you buy a bit of hardware. Hardware is designed to work on particular platforms and if you go out and buy something, again being mindful of the system requirements, things should work out OK for you. This isnt true 100% of the time, but given the billion or so PCs in use, the failure rate is surprisingly low.
Things just work, and given the complexity of that device youre sitting in front of to read this, its amazing that computers hum along as reliably as they do. Mostly this is down to the principals of survival of the fittest being at work if a company produces a product with too many bugs too often, that company is doomed.
But when it comes to Linux, things arent as straight forward. First off, Linux commands a tiny market share. Net Applications shows Linux web usage currently sitting at just under 0.7 per cent. That level of market share is far too small and insignificant to command much sway among software and hardware vendors. While Linux communities like to believe that this 0.7 per cent user base is bigger than it is, and some companies are now paying lip service to Linux, no matter how you look at it, 0.7 per cent is a small number. And even with the best will in the world, the amount of effort that vendors can seriously be expected to put into Linux, given the low market share, is not much. With profit margins getting ever smaller, supporting countless Linux distros just doesnt make good business sense.
Another hidden cost is time. While its true that installing Linux has become quicker and easier over the years, the process is still far from perfect. Some severe problem areas still exist (for example, WiFi adaptors, which is very hit and miss) and if you happen to run into the tar pits, you can expect to be stuck there for a long time. Also, there are more basic things. While Vista and Leopard are ready to play DVDs out of the box, Linux users have to mess about with codecs and agree to legally indemnify everyone for using legally dubious codecs. Sure, you can buy software players, some of which are rather good, but the advantage of a free OS starts to be eroded if you instantly have to put your hand in your pocket.