As a Technical Consultant in the CG industry, I have noticed that a large amount of people starting out in this industry overlook the importance of graphics kit. Seems silly to me. Especially as it is a large part of any visualizer's or 3D operator's workflow.
Generally speaking, NVidia's Quadro FX cards dominate the industries we serve, but why exactly? Part of the answer lies in the exceptional quality and spec of their professional range of cards, but the software used in this industry also plays an important part.
Over the years, the viewports of software like Maya, XSI, 3D Studio Max and others have become more and more graphically intensive. In order to support higher poly models, more complicated geometry and hardware-based workflow, many software companies work with the likes of NVIDIA to produce certified drivers.
This effectively means that each software package will have a driver that they consider to be, "tried, tested and true". The advantage that this gives the software companies is that they can design their software to work best on each platform. Using a specific driver for each graphical chipset means that it is easier to provide support and ensure best possible usability for the artist. The downside is that people using unsupported graphics units, may find only too late that they their hardware is not up to the task.
A professional graphics card is much more expensive than the entry-level, box-standard type card that comes with the average workstation. Technically speaking, our industries demand much more than your average end-user, which can result in problematic workflow for users on unsupported or non-certified hardware.
This doesn't mean that cheaper graphics cards don't work properly, and cannot be used with most software packages. It just means that they may not work and perform as well as expected. For example, a large number of users who experience sluggishness with large scene files may have to do things like working in wireframe as a workaround - which is less than ideal
The upshot of all this is that it pays to be extra vigilant when purchasing new kit. While the above may be fairly obvious to the seasoned professionals, less savvy budding artists need to be sure that they understand what they are buying.