They hang around on Usenet, waiting for your questions. They are your technical support. And rather than folks that are paid to answer the phones, these people are doing it for the joy of sharing knowledge. While that might sound overly romantic, free, accurate, and fast technical support also makes very good financial sense. However, if you really want to pay someone, organizations like Red Hat have full service options, where you can get 24x7 phone and email support, and rapid response to your questions.
Uptime is another big consideration.
Unix machines have uptime measured in months. And, due to some of the underlying designs of the system, when one program goes down, it seldom takes the whole machine with it. Unix is a true multi-user operating system. In fact, X-Windows has been around longer than NT has. Many Unix applications, and, often, the OS itself, come with source code.