You can try Synergy?doesn't sound very likely to me personally, using extended desktops is usually aimed at multiple monitors connected to the single computer, not as you describe, however you can usually connect an addition monitor to laptops and do it that way fine.
You can try Synergy?doesn't sound very likely to me personally, using extended desktops is usually aimed at multiple monitors connected to the single computer, not as you describe, however you can usually connect an addition monitor to laptops and do it that way fine.