VGA and DVI

here is the problem:
i bought a new pc screen
i have a pc (and a vidfeo card: x1600 with VGA and DVI)
i have an xbox 360
my xbox 360 can only be connected to the VGA on my video card
my screen can be connected to the DVI on my video card
but when i connect my screen to the DVI, nothing happens i have tried a lot but nothing worked
how can i tell my video card to show the DVI input?(dont know if this is needed, i am very confused)
what do i have to do? (maybe a better question than the one above )
Answer #1
The videocard should output DVI automatically when it is connected. It’s possible that the screen is faulty.
Answer #2
If you right click on the desktop you should be able to select the ATI Catalyst control centre.
Select Display Manager and try to set up the secondary display..
Answer #3
do i have to do this while the screen is connected to VGA?
or do i need a second screen on VGA, and the new screen on DVI(because if i configure it now, while the screen is connected to VGA, it would find nothing on DVI)
EDIT:
i just turned off my pc, disconnected all VGA and connected my screen to DVI…nothing happened when i wanted to boot my pc, it just said “no cable connected”
Answer #4
Some screens have to be manually selected for the input line #1 or #2 – have a read of your manual.
Answer #5
i found it i think, my dad wanted to install my screen and he used the wrong cable, it was not DVI that he connected -.-
i told him i can do it myself but no listen eh ^^