There is a very nice opensource / freeware tool you can use to control multiple PC’s like KVM. It’s compatible with Linux, OSX and Windows.
What is Synergy?
Do you have two computers at your desk, with two screens and two sets of keyboard and mouse? Here’s where Synergy comes in…
… Synergy is Free and Open Source Software that lets you easily share your mouse and keyboard between multiple computers, where each computer has its own display. No special hardware is required, just a network connection. Synergy is supported on Windows, Mac OS X and Linux. Usage is as simple as moving the mouse off the edge of your screen. You can even share your clipboard.