multi monitors

have decided I want to expand my flight simming and use 2 monitors with FS2004. One for instruments, the other for out of window view. I am unsure of what I need to do. Someone told me I need a dual head video card (at least 256 mg), while I also read that you can use 2 PC's and 2 monitors, with the main PC holding fligh sim program, the second PC for instruments, networked to the main. What is correct? How do I network?
How 'big' do the PC's need to be? Is there a web site that explains all this?
Need help badly...