Yes as good as source can be especially as MS change things every week, Im part of a irc network which used to do bad things (released Win 2003 before MS and office 2003 ) but now works with MS and serves windows alpha and beta software, inc longhorn/vista/office 12 and have being doing so before most in public even knew about longhorn.
One guy worked for MS other used to work for AMD and has good contacts, thats also who gives us the software before anyone else, and YES MS are there and turn a blind eye as they get 1000's of free testers instead of paying a few hundred so longs we dont serve Retail final software (were allowed to serve SP2 before MS did to admins or later public as not retail software and its FREE.
I thought it was common know how thats your going to get DX10 for XP, cause Ive alway read that in reports, but it will be after Vista and again Id guess with SP3.
BTW, MS annouced lifespan of XP not too long ago and its going t have a SP3, now hardware makers who make gpus wouldnt be happy if everyone on XP didnt buy their DX10 cards as they would either not run or only run DX9C, infact there is another build above 9C which aint 10, but as I BBL gotta run and I will try get more info but not naming anyone.
The games and apps made for vista not running on XP has nothing to do with DX10, just Vista is totally different from current windows where as XP was able to run most 9x games (not all) and windows 2000 drivers when lack of XP ones when OS was new, this time round you wont have this luxury.