Despite Dell's own statements about the quality and security of Linux (Ubuntu in particular), it seems that they have now dropped Ubuntu support from their website. As of now, Dell is no longer selling Ubuntu based machines from their website.
I'm continually astounded by the fact that more people don't use Linux. Economics should dictate that when people want Ubuntu, and it sells well, they increase their offering. The problem with Operating System economics is that there is a huge fear of changing operating systems, making lock-in much worse than with normal market economics. The other piece is that Microsoft has an established monopoly. In order to use the software someone wants, that software has to be built for one or more operating systems. Most people can't switch to a better, higher quality, lower cost solution because their software is built for a specific list of operating systems (GoToMeeting, Adobe Products). This lock-in hurts consumers, and prevents better options from being a choice.
This problem has been alleviated somewhat by web-based software, but the problem continues to this day. This is why it's so saddening that Ubuntu is giving up their Ubuntu offering.