Back in 1996, home PC graphics cards were strictly 2D only with 3D hardware being limited to high-end graphics workstations.
NEC were one of the first companies to develop an affordable 3d card aimed at the PC games market, with their PowerVR chipset. The card quickly gained a reputation as being technically impressive, if you had a fast enough CPU to run alongside it, and if you could find games that supported it- At the time, there was no such thing as DirectX, so NEC implemented their own API. Any games which wanted to take advantage of these cards had to have large sections of code totally re-written.
At roughly the same time, however, 3DFX released their Voodoo card with it's Glide API which was much more popular both with developers. As a result of this, people bought the 3DFX card that their favourite games required and the PowerVR was quickly forgotten.
The second generation PowerVR2 chipset was released in 1998 where again, in the PC market it lost out to 3DFX's latest offering, the Voodoo 2. However, it received a major boost when Sega selected it to sit alongsite the Hitachi SH4 CPU in the Dreamcast console.
In a console environment with games written specifically for the VR2, the power of the chipset became clear. Graphically advanced games were released which looked good even compared to their PC counterparts right up until the end of Dreamcast production in 2001.
Returning to the PC market, the Kyro chipset was essentially PowerVR3 - NEC's attempt to keep up with 3DFX, ATI and nVidia's latest 'all in one' 2D and 3D cards, where they unfortunately continued their trend of failing to offer high enough performance at a low enough price to match the competition.
Which brings us to today- The Kyro II is the latest PowerVR based chipset which tries to compete with the Nvidia GeForce and the ATI Radeon GPU architectures. By all accounts, it performs well and with DirectX around to provide programmers with a single programming interface into all three cards, it might finally have a chance of succeeding.