PureVideo HD is supported by some GeForce 7-based graphics cards where you combine hardware accelerated encodning of high resolution video signals with circuits for HDCP encryption which will be required in the future to play these formats with a PC. The problem today is that there are very few HDCP-capable graphics cards available where only the new GeForce 7950GX2 series sports the technology from scratch.
"A graphics card featuring PureVideo HD technology combined with an AACS HD disk drive, an HDCP-compliant display and a PureVideo-powered HD movie player from companies like CyberLink, InterVideo and Nero make it possible for consumers to enjoy superb HD movie playback on their PC."

PureVideo HD is expected to appear in NVIDIA's graphcis card drivers within a month and since there are very few HDCP-capable NVIDIA graphics cards available now there is no real rush. To be able to make use of the technology you also need a HD DVD/Blu-ray player and compatible software.
It seems that NVIDIA has now started to get ready for the coming of the HD formats and it is about time, it's especially sad for all of those who just bought a new graphics card which doesn't sport HDCP, something we've earleir reported is a problem for both NVIDIA and ATI.