Thanks a lot for your answer
There are few things to say concerning your answer:
1) The link to the howto doesn't work
2) Your explanation for the stamina/speed switch looks very similar to the standard one (explained in other posts) that didn't worked for most of us. Anyway I'll go through it, compare it with the former ones and see if it works.
My main problem is that I only have ubuntu in my laptop so I cannot follow the procedure of booting into windows to make it detect the card and then reboot to linux. My two lights are always off and I don't even know which card is using ubuntu. Knowing which one is under use would be a good starting point. Someone has an idea?