Hi (sorry for the spaniards for this article in english but I just want it to have bigger audience).
I just want to show Internet people the solution for my problem in order to help other people to solve similar one.
I had an Asus motherboard (P5K-VM) and I installed Ubuntu Linux (8.10 intrepid ibex) with the graphical feature of this motherboard (no graphical card).
One day I bought a new monitor (a present from my wife), with DVI input. So I decided to buy a graphical card because I wanted to use that feature. The card was an Asus EAH3450, so I plugged it in the motherboard.
Suddenly Linux converted in a black screen.
The solution:
1.- Unplug the card and start Linux again from the graphical card integrated in the motherboard.
2.- Install Envy (Alberto Milone: thanks).
3.- Shutdown the computer and plug the new graphical card.
4.- Start the computer with the DVI cable, and in GRUB select protected mode.
5.- Choose the "start root" option (similar text).
6.- Execute "envyng -t"
7.- Choose to intall ATI driver and restart.
8.- Linux should start with the new driver.
I hope this entry can save the life to someone else.
Bye,
jmrlegido