LAGU:
I have read in the User manual the factum I can use my LCD screen and view another VGA screen through a special adapter as I should connect to the outlet of the VGA screen and then to the special outlet back the computer. I was first thinking of control 2 computers and remove the VGA screen but I must be wrong. I think both screens must be on so I can change between them or can the VGA screen bee off and I yet can view it?
If I understand you correctly, were you wanting to run multiple computers into a single monitor? If so I purchased a device for doing just that from Best Buy. It is called a 4-port KVM switch with audio support. It is made by IOGEAR and is model# GCS614A. It allows you to manage four PS/2 computers from a single PS/2 keyboard, PS/2 mouse and monitor. Admittedly I have yet to test it because I let my son take his computer back before I had a chance, but I do intend to build more systems and run them all from the same mouse, keyboard and monitor setup.

I imagine there are other vendors who sell similar items, but from your post this looks like what you were wanting to do.