The article was more about the M$ reasons why DX10 would only be available on Vista and it was though to be nothing more than marketing for Vista. One by one the author was knocking of the reasons as to why you had to have Vista and the biggest one was DX10 was supposed to be able to use virtualisation (or something like that). Since the graphics manufacturers were having such difficulty that requirement was quietly dropped, effectively meaning that DX10 could run on XP.

We will have to wait and see if that will be the case or if M$ will keep insisting that you need Vista to run DX10 games.