Experiences When Transitioning to Low-End Workstations?

gerddie asks: "Lately, we have seen a lot of companies starting to move their graphics stuff from high end to low end linux workstations (e.g. Dreamworks). Of course one reason to do such thing is cut costs, and therefore, at our institute we are going to replace or aging SGI O2s with Linux workstations. I wonder if you have experience with such a transition - especially regarding the usability of such machines for (scientific) visualization? What is working well, and where did you encounter pitfalls?"