I know many people using Vista had problems tu run JK on it.
I've been asking around, and finally ShadowX has come to the rescue of all those who use Vista and couldn't figure it out.
Here it is:
Originally Posted by ShadowX
First, right-click jk.exe (wherever you installed Jedi Knight), set it to Win XP SP2 compatibility mode, and check Disable Visual Themes and Disable Desktop Composition.
If you're using a GeForce, get the latest official drivers, then in the NVIDIA Conrol Panel, create a custom profile for jk.exe under Manage 3D Settings then the Program Settings tab. Disable Antialiasing, Transparency Antialiasing and Comformant Texture Clamp for jk.exe (everything else works, but antialiasing will make JK crash every time, sadly).
Now, you may luanch JK and see nothing but hear the mouseover sounds of the buttons if you move the mouse. Alt-tab out of JK, then tab back in, and the menu will appear. Unfortunately, going between the 3D and the menu will always require this, so it will be a pain doing all your settings again if you forget something and have to go back into the menu, or when you're joining/leaving games. Otherwise, the game actually runs! I run JK in 1080p now compared to 320x400 when I first got the game... LOL!
Thanks a lot, Shadow!