Hi,
I have tried to run my application on few PC-s. The computer I use for developing runs fine, but when I ran it on my laptop lighting was bad and fps low (first it gave some asserterrors (assertion was off?) which I cached bluntly with Throwable just to get it running).
On another PC it gave me unsupportedoperationexception about something that my hardware can’t do.
So my question is, how can I tune JM as low as I can to run things on a worst possible PC?
First try installing the latest graphics drivers on the laptop.
and after you do that, post the stack traces and assertions errors. 
For the lighting issue, make sure you set shininess on all materials
I am pretty sure my laptops drivers were up to date, unfortunately it is at “guarantee remont” (no idea how to say it correctly) graphics card needs replacing I think (yes yes :D).
And unfortunately I can not test it on the other computer that gave me exceptions, because it is in the university.
All I remember is:
Unsupportedoperationexception: something about “Point … not supported on the underlying hardware”.
It gives no problems for me on the PC at work and on the PC I am currently using.
Though when I set AA on the PC at work then I also got some exceptions.
Whats the exception you get when you set AA?
Only when I set AA higher than 4:
INFO: Using LWJGL 2.5
31.01.2011 8:26:13 com.jme3.system.lwjgl.LwjglDisplay createContext
INFO: Selected display mode: 1280 x 720 x 0 @0Hz
31.01.2011 8:26:13 com.jme3.app.Application handleError
SEVERE: Failed to create display
org.lwjgl.LWJGLException: F
at org.lwjgl.opengl.WindowsPeerInfo.nChoosePixelFormat(Native Method)
at org.lwjgl.opengl.WindowsPeerInfo.choosePixelFormat(WindowsPeerInfo.java:52)
at org.lwjgl.opengl.WindowsDisplay.createWindow(WindowsDisplay.java:185)
at org.lwjgl.opengl.Display.createWindow(Display.java:315)
at org.lwjgl.opengl.Display.create(Display.java:855)
at org.lwjgl.opengl.Display.create(Display.java:783)
at com.jme3.system.lwjgl.LwjglDisplay.createContext(LwjglDisplay.java:113)
at com.jme3.system.lwjgl.LwjglAbstractDisplay.initInThread(LwjglAbstractDisplay.java:98)
at com.jme3.system.lwjgl.LwjglAbstractDisplay.run(LwjglAbstractDisplay.java:193)
at java.lang.Thread.run(Thread.java:619)
31.01.2011 8:26:13 com.jme3.app.Application handleError
SEVERE: Uncaught exception thrown in Thread[LWJGL Renderer Thread,5,main]
java.lang.IllegalStateException: Cannot determine close requested state of uncreated window
at org.lwjgl.opengl.Display.isCloseRequested(Display.java:581)
at com.jme3.system.lwjgl.LwjglAbstractDisplay.run(LwjglAbstractDisplay.java:195)
at java.lang.Thread.run(Thread.java:619)
Yeah thats a known error. If you set higher AA than your system supports it crashes. We just need to add proper detection of maximum supported AA level.