If a distribution's duration and activity isn't enough to ease concerns, check the licenses. Most software in a distribution is released under the GNU General Public License, which gives you the right to a copy of the source code. In fact, distributions publishing under this license are required to either give you the software or offer to do so at nominal cost for copying. Assuming you have a Linux expert or two on staff, if your chosen distribution does go under, you can legally continue developing it for your own needs.
5) What training and support are available?
If you want traditional support, you can find it with most commercial distributions although you should make some comparisons to see what the current market rate happens to be. Training is less widespread, and, although Red Hat does maintain one of the leading certification programs, in many cases you may want to fall back on generic training from Sair Linux or the Linux Professional Institute.
However, even with commercial distributions, paid support and training are often last resorts. Even the smallest distributions offer free mailing lists and IRC channels for front-line help.
And if you're tempted to dismiss this free help as haphazard, think again. In more cases than not, these informal resources provide quicker and more reliable help than the traditional phone lines. Often, they give you direct access to people who designed and wrote the software you're struggling with.
Best of all, unlike with paid support, you can monitor the informal support available for a distribution before making your choice. After you do, you may decide that you don't need to choose a commercial distribution at all, or that, if you do, purchasing help is unnecessary.
6) What are the options for software, security and updates?
On Linux, software is usually installed via packages, or collections of files and scripts for automatic configuration. A few use archived files, and some individual pieces of software use third party installers, but most use a packaging system. The most popular packaging systems are .rpm and .deb, both of which check for other software youll need to run a package and offer to install it for you.
This installation is generally done from package repositories on the Internet. Many distributions maintain separate repositories for security updates. As a result of this system, after installation you may never do a complete system upgrade at any one time. Instead, you may do a series of small, regular ones.
Before committing to a distribution, check the software in the repositories. Some smaller distributions may have a limited selection, especially if they use a non-mainstream packaging system. They may still have all the software that you need, but you need to know upfront.
Check, too, how the distribution handles security updates. Is there a mailing list that announces bugs and updates? If the distribution is commercial, do you have to pay for updates? Is the distribution in touch with other projects like the Apache web server, so that users receive the earliest possible notice of security problems?
You might also want to search the Internet to try to get some sense of how quickly the distribution responds to known problems.
7) How easy is the distribution for desktop users?
The majority of distributions provide some sort of desktop for non-expert users. Many even include themes and desktop wallpaper that will make casual users believe that they are using Windows. However, a few like Mandriva and Ubuntu make special efforts to provide user-friendly tools.
You should also be aware that some distributions make a philosophical point of shipping only non-proprietary software. In such a case, if extras like Java, Flash, or Acrobat Reader are important to your business, you'll need to install them separately, no matter how easy the distribution is to use otherwise. Search a distribution's web site or CD image, and you can often find a list of software that is installed.
8) What other specializations do you need?
With all the available distributions, Linux offers something for everybody.