Two computers & two monitors

I have two computers & two monitors.

I'd like to be able to do the following with a flick of a switch or something easy:

1) to use both monitors with computer A;
2) to use both monitors with computer B;
3) to use one monitor with computer A and one with computer B (being able to cut & paste a la Synergy would be a bonus)

At the moment using a KVM I can switch between (one monitor & computer A--and lose the functionality of the other monitor and access to computer B) and (two monitors & computer B--having lost access to computer A)

Is there any way of having it all? Any ideas?

I have a vague idea that using Synergy and the KVM together might do it, but I can't quite wrap my head around it.

(Sorry if this isn't the right forum for this question: I couldn't figure out where it should really go.)