Hello all 
After reading this post about nVidia GT 555M and intel CPU: http://forums.freebsd.org/showthread.php?t=26751
The general question is :
To make FreeBSD 9 work with the nVidia driver and 500M series, the BIOS of the laptop must have two options:
1- choose Intel graphic / nVidia graphic
2- disabling nVidia Optimus option
Then, with thoses options, choose nVidia graphic/disabled Optimus and FreeBSD 9 will be OK.
Is that correct?
GeForce 500M series:
GTX 580M, GTX 570M, GTX 560M, GT 555M, GT 550M, GT 540M, GT 525M, GT 520M

After reading this post about nVidia GT 555M and intel CPU: http://forums.freebsd.org/showthread.php?t=26751
The general question is :
To make FreeBSD 9 work with the nVidia driver and 500M series, the BIOS of the laptop must have two options:
1- choose Intel graphic / nVidia graphic
2- disabling nVidia Optimus option
Then, with thoses options, choose nVidia graphic/disabled Optimus and FreeBSD 9 will be OK.
Is that correct?
GeForce 500M series:
GTX 580M, GTX 570M, GTX 560M, GT 555M, GT 550M, GT 540M, GT 525M, GT 520M