Based on over 2 years of experience helping many people editing and playing JK, I have these suggestions:
1. Do NOT install the DirectX 5 stuff that is part of the JK installation. Most likely an XP system will have a much more recent DirectX already installed.
2. Do NOT use any compatibility mode; JK and MotS run just fine without them.
3. Do NOT install LucasArts' 1.01 patch. It only fixes an obscure joystick bug, and the (exe) patches
on the JK Editing Hub
will not work with 1.01.
4. Please describe what you mean when you say "it doesn't work". Does JK's installation finish? What is the error message that shows up? At what part of setting up or running JK does it mess up? Does JK crash (JK closes unexpectedly) or freeze (won't let you do anything with JK, but shows the last screen you were on)?
5. Do NOT run JK's launcher; run the JK.EXE file directly. Do NOT run the JK.EXE from the CD; run JK.EXE from the hard drive where JK is installed.
6. If you can open JK, but it crashes when going into game, then the video settings within JK are likely the cause. This can occur even if JK worked the last time, because there are times when JK "randomly" selects the wrong mode; you just need to double-check the settings to make sure they are correct. Open JK, choose your player, click on "Setup", and then click on "Display". Verify that the selected mode under "Avaliable Video Modes" is correct for your video card. If in doubt, choose 640x480; if that setting crashes JK when you go into game, then a video driver is likely the problem.