Need Help Thinking Through a Dual Monitor / Dual Computer Set-Up

[dabluebery]

Ok. I'm not technically retarded, but there's so much noise on the Internet that I need help thinking through what I need / what is realistic based on the following criteria;

I have the following in my home office;

2 desktop computers, old and new
2 monitors (Dell 2001FP and an old 17" CRT)

Currently, I have a dual monitor setup on my new computer, but I need to connect the old computer. This is what I want to be able to do;

1) Be able to use the 2nd computer with my current mouse and keyboard when necessary.

2) Be able to have dual monitors set up on my new computer when necessary, to 8-table or similar.

3) Have a second mouse and keyboard available to use the second computer and the second monitor when necessary. (My wife needs to shop on the Internet and I'm playing poker blah blah blah)

4) [Possibly overkill;] Run both computers simultaneously from the same keyboard and mouse. 1 computer on 1 screen, one on the other. No switching back and forth. Is there a piece of software that can handle this?

Can someone wade through my nonsense and tell me what software and peripherals I'm looking for? Also, if I've been unclear, I'll be happy to further elaborate.

Rob