Dual Display Issues, Mini Display Cable, Firewire, USB, Nothing Works

I am working on a project for my supervisor, the specifics of each machine are listed below to the best of my ability:

Machine 1:

iMac9,1 Intel Core 2 Duo

Version: 10.6.8

Build: 10K549

Machine 2:

iMac10,1 Intel Core 2 Duo

Version: 10.6.8

Build:10K549

I have a iLuv Mini DisplayPort Cable, a 9-Pin to 9-Pin Firewire Cable, a M/M USB Cable and an ethernet cable. What I have been trying to do is link these two computers together so that each can be used as a seperate processor but their screens can be shared. Before anyone tells me this is impossible, these two monitors have in the past been connected together so there was the ability to dual use the computer monitors. I do not remember if I actually had the processing power of both available. When I plug the minidisplay port cable from one computer to the other the screen on Machine 2 will blink black to blue and then go back to an independent screen. The displays tab on neither computer shows two displays and none of the command f2 or f3 prompts are causing either computer to respond. I have tried connecting them with firewire and USB and can only get disk transfer mode from the Firewire. I know these computers used to be able to support being connected to one another and now I have no idea what is going on. I don't personally remember having a minidisplay port cable in the beginning so its possible I am going about this all wrong. I have called Apple Support many times and they suggested an OSX reinstall. I found the reinstallation software for 10.6.3 for a macbook 13 inch and each computer recognized the disc but said that the operating system could not be installed. At this point I have done everything I can think of including running a hardware test through the diagnostic tool at startup and on both computers the test came up with no error codes. Please please help me get these computers working again for my boss!

-Alan