Of course, video editing is dependent on hardware and what would be taxed by Vista is also a drag in editing. But that is not the real story.
Background - I edit with Pinnacle/Avid/now Pinnacle again/ Liquid. Pinnacle worked with ATI in the 2001 timeframe to create an editor that took advantage of the GPU and its strengths, graphics. Non-Linear Editors use digital frames of 'graphics'. So, Pinnacle released a new render card based on the ATI 8500 AIW card that used DirectX to render effects and do playback. The first significant GPU usage for an editor.
Since, the engine has been updated to DX9 and has 100's of effects that can be rendered AND playback of HD is done significantly through the GPU for non-final effects (render on the fly). So much so that HDV1080 is recommended to use 16x PCIe and minimum of 256MB of video memory.
Enter DX10, with a new VM engine for graphics, new calls, etc. Enter Vista, with the first mainline X64 Windows (off the shelf Windows - XP 64 was still 'custom' order). No longer is graphics memory, first in wins. Application address space can now be larger than 2GB (1 hr of HDV MPEG is 13GB).
Pinnacle has publicly said that the next Liquid engine will be redone to support DX10 effectively (meaning it probably will be Vista only). Also, the larger address space is very tempting and hints of a 64 bit version were in a speech. But, release will probably be 2009. NLEs are VERY complex as they stream audio and video from various sources at the same time. It is not something you code in 5 minutes. An example is one of my current workflows. I have the captured video (it splits them into seperate tracks) on my E: drive. I have a voice over and music track (in a different directory on E: for imports and capture). I have an imported graphic for the lower third (bottom of the video - think of a logo like the Peacock or a news ticker). That is resized, so the rendered effect is on F:. If I add color correction to the main clip, it gets read from F:.
So, I can have 3 reads from E: in three different directories and 3 from F: in the same directory (I think), all streaming .... hopefully.... with the GPU rendering some of the effects on the fly. If you can preload a bunch of that because you have 16GB on your system, much better playback than having to do the sparse reads that NLEs do now because of the restrictions of address space and hardware.
Is it better now? I have not done enough yet as I finally loaded Vista on my editor this weekend. A couple of the braver souls report some performance gains in rendering (live). We will see. Is it a detriment? Only if not supported, which is a risk with the $$$ editors.