As this article suggests, perhaps Apple has beaten Linux to the Unix desktop. I still believe that the only way to get a good Linux desktop is to get a computer manufacturer to get behind Linux from the ground up. (MPC, I’m looking in your direction.) If a smaller OEM were to design a line of completely open and dedicated to Linux PCs, they would have some success perhaps even make a killing.
Design the hardware to only work with Linux, any Linux distro. Let the customer pick whatever they like, and outsource the support to the Linux distros. If you want Ubuntu on it, then go to Ubuntu for support. Ubuntu would have no problem supporting hardware they KNOW WORKS with Linux. Same with all the other distros.
The OEM could start with an open BIOS and then make sure all drivers are open to all included hardware. If the user choses to swap out a video card say, then the user takes responsibility for his own drivers. The OEM would only support included hardware. Most people and businesses do not muck about in their machines. Only Geeks.