Things are not much different than you found here: Intel D945GTP 3.5mm Drivers for Windows 7
What drivers there are can be found here: Intel® Desktop Board D945GTP
You might get lucky and get vista driver to work. Personally, I would toss the board in the recycle bin. That next best thing you can do is to get an audio card.
This message was posted on behalf of Intel Corporation
The Intel® Desktop Board D945GTP only supports Windows® (Vista – XP- 2000);
Supported Operating Systems for Intel® Desktop Boards:
Please let me know if there is anything else I could do for you.