Just reading the current PC Format (December) and it seems the Windows Vista technologies (Windows ReadyDrive: hard disks boot up faster, resume from hibernate in less time, preserve battery power, and improve hard disk reliability) will be a feature of new motherboards ... so not an external (Universal Serial) Bus device.
This, plus the missing supporting features for Core 2 Duo, and the imminent arrival of DX10 make me think that I shall wait for a bit before making my new PC.
There is a great article on the new technology in DirectX 10, too: unified shader architecture:
vertex (integer) shaders get overworked outside doing trees and distances,
pixel (floating point) shaders get overworked inside, doing oily / transparent surfaces, and the other types of shaders are idle; plus
SM3 (floating point) fog effects.
Added to this is (geometric) SM4 (little triangles, rather than just the intersection of two lines, like vertex shading).
DirectX9.L will allow DirectX10 cards to run previous DirectX9 effects (and not vice versa), because DirectX10 is a complete re-write of the specification (not done since the invention of DirectX back in Windows95).
Though the next DirectX cards (due out early next year) will be long superceded before DirectX10 games become common, ATi's R600 looks to be a much better interpretation of the standard than nVidia's ... so I might just see what I can build for