I have both computers connected via a KVM switch and use one monitor, keyboard, and mouse - all of this installed and the second "old" computer running with the idea of experimenting with Linux on a hdd install.
So, from your post I gather that all that is really necessary is a Fat 32 partition on one of the drives to put win programs if I want to try to run them. WINE, etc, doed not rely upon finding the win kernal or whatever somewhere on the computer?