Yes all cables where connected and the new drive removed. I however already found a solution for this problem.
I set the CMOS jumper to the reset position ( while all drives disconnected ) and tried to boot, to boot worked but since the jumper was set to reset, it didnt get any further than that. After setting the jumper to keep again and connecting the original HD, the system booted like nothing ever happened.
Connecting the second drive appears to be more difficult than expected and i will have to do some more research on installing extra IDE drives when you have a SATA drive.
Thx for your quick response!