In a word (the first 2 pages I read), JC loves dx9, says there is no need to jump on the new graphics hardware (G8x or R6xx) and will keep on using winxp:
"but there’s no huge thing where we’re dying to use any particular DX10 feature"
"Personally, I wouldn’t jump at something like DX10 right now"
"Quake Wars is definitely not DX10"
"I don’t think that there’s any huge need for people to jump right now. All the high-end video cards right now—video cards across the board—are great nowadays."
"It’s a tough thing for Microsoft, where, essentially, Windows XP was a just fine operating system"
"Nothing is going to help a new game by going to a new operating system"
"There were some clear wins going from Windows 95 to Windows XP for games, but there really aren’t any for Vista."
"I suspect I could run XP for a great many more years without having a problem with it."
and here is a topic on carmak's interview on Beyond3D:
http://www.beyond3d.com/forum/showthread.php?t=37507
