Thinking about it, i have come on with the solution. And its not looking good for me.
The spare PC is connected to my 8 port KVM. It uses a VGA cable, so i have a VGA output from the computer to the KVM to the screen, but the screen also has DVI, so i have a second cable from my spare marchine to the screen for better picture if i need it. When install, it would show on both screens. So i would just use the VGA/KVM input. Once it booted in to windows for the first time, it would see that DVI format was better, or just select that one, and choose to display the install on that screen. I still had the screen set to VGA and so saw only the black screen with the 'Windows 7 Beta' text botton corner.
So after 4 disk and about 10 installations, it looks like they all worked fine! And it was only a simple task of unpluging the DVI cable that made the installation show on the VGA screen input....
My have i been dumb. Lol.
So, sorry for wasting your time. And remember kids, check all your screen outputs!