Input Director is a Free application which will help you to share your keyboard and mouse with multiple computers. This application is free for Personal Non-Commercial use only.
Input director is an easy to use keyboard and mouse sharing application. The requirement is that you need to be on a network, and all systems need to have installed the Input Director. I just used it on my Windows Server 2003 and Windows 7 Ultimate systems, and it worked perfectly fine.
On Global preferences screen you can set the startup options. SO that the application will run as Master/Slave when you startup a system and you can access it from log on screen too.
in the Master preferences you can set the keys which will work as Alt+Control+Delete and Lock Workstation keys, you will need this if your slave computer need to press al+control+delete to get the login screen.
If you are using multiple systems Input director is a cool handy application which will allow you to use a single Keyboard and Mouse with multiple computers with out any hardware. If you are looking for a hardware, you may buy a KVM switch which will allow you to share Monitor, Keyboard and mouse with 2 computers. you will have to manually click a switch to transfer control to next computer.
Transitioning control to another computer is a simple as moving your cursor off the screen on one computer for it to jump to the other
Able to control a computer without needing to login to it first
Compatible with Vista User Account Control pop-ups
Simultaneously lock all computers
Synchronize the screensavers across your computers
Synchronize shutdown of your system (or individually configure whether a computer goes to standby, hibernate or shuts down)
Encrypt network data between Input Director controlled computers using AES with a 128, 192 or 256bit key
Lock down the Input Director configuration so that only Administrators may make changes
Systems can limit which master systems can control them by host name or network subnet
Ripples surround the cursor for a few seconds after transitioning to help the eye follow the cursor from one computer to another
On startup slave systems will inform the master system that they are available
Input Director Home page
Input director, How to use - Input director quick start
Input director support clipboard sharing but drag and drop will not work between two different computers. If you want to share keyboard and mouse with multiple computers running different operating systems (Other than windows) you can try Synergy. You can read a comparison on Input director and Synergy here
[Via Amit @ Digital Inspiration]