Oi!! Problem, help would be greatly appreciated

[GiMpY-wAnNaBe]

I just upgraded my computer from a PIII 866 with built in videocard and an extremely crappy set up to an AMD 2500+ with a radeon 9600XT and an asus motherboard and 512 RAM and a new case. So i took the stuff that i need from my old case and started putting it in my new one, i've got everything wired up properly, the problem is that when i start up the computer, the bootup will go normally, but when it's supposed to go to the windows loading screen, the screen goes blank....nothing....my monitor gives its "no signal detected" message and nothing happens. I connected my hard drive to my dads computer and the hard drive refused to work at all, so i reformatted it and installed windows a-new on it. When i go back to my computer to retry it, the exact same thing happens. Is there some compatibility issue between AMD processors and ATI videocards? Do i need to do something for the AGP slot? What the hell is going on??????



All help is greatly appreciated, and will be returned with +rep