DirectX 9 updates got very chaotic after they started to release bimonthly updates without changing the version number... from time to time you can still notice a thread on gaming forum from perplexed people which found that their game worked after 'reinstalling' DirectX 9.0c, when in fact it just added the latest updates.
After all, if you have DirectX 9.0c and a game asks you if you want to install DirectX 9.0c without detailing anything about the bimonthly update, you are supposedly going to click on cancel...
At the time, I had the latest update (February or April 2007)... since on Vista I tried with the current release, you could be right. I'll give it another go with XP and let you know.
For anyone interested, here there are both the latest full version DirectX 9.0c and the individual bimonthly updates:
http://filehippo.com/download_directx/
After all, if you have DirectX 9.0c and a game asks you if you want to install DirectX 9.0c without detailing anything about the bimonthly update, you are supposedly going to click on cancel...
Re drivers, installing June2007 DirectX update on XP machines may also be a factor, you may have similar version on your vista install?
At the time, I had the latest update (February or April 2007)... since on Vista I tried with the current release, you could be right. I'll give it another go with XP and let you know.
For anyone interested, here there are both the latest full version DirectX 9.0c and the individual bimonthly updates:
http://filehippo.com/download_directx/