How can I control two computers (with seperate monitors) with the same keyboard and mouse? Is there a software solution to this? Can the computers be running different OSs?
There is this open-source software hosted on Sourceforge.net:
Synergy lets you easily share a single mouse and keyboard between multiple computers with different operating systems, each with its own display, without special hardware. It's intended for users with multiple computers on their desk since each system uses its own monitor(s).
Redirecting the mouse and keyboard is as simple as moving the mouse off the edge of your screen. Synergy also merges the clipboards of all the systems into one, allowing cut-and-paste between systems. Furthermore, it synchronizes screen savers so they all start and stop together and, if screen locking is enabled, only one screen requires a password to unlock them all.
Another free software (only for Windows):
Input Director is a Windows application that lets you control multiple Windows systems using the keyboard/mouse attached to one computer. It is designed for folks who have two (or more) computers set up at home and find themselves regularly sliding from one system to the other (and wearing out the carpet in the process!).
With Input Director, you can share a single keyboard/mouse across a set of systems. You switch which system receives the input either by hotkey or by moving the cursor so that it transitions from one screen to the other (in a very similar fashion to a multi-monitor setup). The idea being that you can position the monitors from two or more systems in a row and use a shared keyboard/mouse to control all of them. Input Director also supports a "shared" clipboard, in which you can copy data onto the clipboard on one system, transition across to another and paste.
Input Director requires Windows 2000 (Service Pack 4), Windows XP (Service Pack 2), Windows 2003, Windows Vista, Windows 2008 or Windows 7. The systems must be networked.
See this blog post which explains some differences between the two programs.
There is a hardware solution as well, so called KVM (keyboard, video, mouse) switches:
A KVM switch is a hardware device that allows a user to control multiple computers from a single keyboard, video monitor and mouse. Although multiple computers are connected to the KVM, typically a smaller number of computers can be controlled at any given time.
Synergy hasn't been updated in years, I would suggest you to use Synergy+, its a fork of Synergy that is under active development.
Mouse without Borders is a product that makes you the captain of your computer fleet by allowing you to control up to four computers from a single mouse and keyboard. This means that with Mouse without Borders you can copy text or drag and drop files across computers.
Supported Operating System:
Windows 10 , Windows 7, Windows 8, Windows 8.1, Windows Server 2003, Windows Server 2008, Windows Server 2012, Windows Vista, Windows XP SP3
Windows 10, Windows 8.1, Windows 8, Windows Server 2012, Windows 7, Windows Server 2008, Windows Vista, Windows Server 2003 or Windows XP SP3 (32/64 bit)
At work, I have two computers each with its own monitor (Windows 7, Windows 2003 Server).
The first one is controlled with the keyboard and mouse, the second one is controlled from the first one using Terminal Services.
This solution works pretty well for me and my coworkers (I'm a kind of evangelist of this poor man, but effective, solution).
Maxivista will do this, plus it will also let you use the screen of the second computer in a multi-monitor configuration with your primary computer.
Have a look at Synergy:
Synergy lets you easily share your mouse and keyboard between multiple computers on your desk, and it's Free and Open Source. Just move your mouse off the edge of one computer's screen on to another. You can even share all of your clipboards. All you need is a network connection. Synergy is cross-platform (works on Windows, Mac OS X and Linux).