[Lilux-help] Which "Enterprise" Linux?

I have a question for all of those who use Linux at work. I am aware that there are 2 major "enterprise" distros which are of course RedHat and Novell/SuSE. Besides those, Mandriva, Ubuntu and especially SunJDS all have commercial offers. But which distros are _really_ used (on servers) here in Luxemburg, or in Europe? Is RedHat also dominant here? Do companies always go for commercial solutions, or are the non-commercial ones catching up (I heard of Debian being used on a major site in Luxemburg, and also being used in Munich)? If so, how is support organised? The point of my question is not to find out what one should use at work, but what is actually used, i.e. what decisions companies have taken in the past. I suppose it is best not to mention the companies explicitely. Thanks for your input.