Hello spcxxx,
It is important to mention that the IRST supported versions for XP for the P67 Chipset (PCH) are the ones that appear using the filter in downloadcenter.intel.com. You can check this at the image below.
I also noticed that the driver you mention seems to be an OEM driver and the equivalent driver from our side is the version 9.6 which does not support the PCH chipsets.
Based on the .INF file from the driver 12.8 that I provided before, it should support XP. This is not listed under the supported operating systems because XP was removed from support my Microsoft some time ago and it is also reflected from our side. You can check the attached .INF file below.
It is great to hear from you that the driver version 9.5 is working for you under the P67 chipset but honestly it should not be working. You can try it as it is working now but we cannot guarantee the functionality.
