Input Director

Input Director is a free program that enables two or more computers connected on a network to share a single mouse and keyboard input, allowing for dragging a mouse pointer across multiple screens. This easy to set-up software also enables the sharing of clipboard contents, including copying/pasting files and folders across multiple computers.

Read the article HERE.

You might want to check out Synergy2 as a compare-and-contrast. It doesn’t do the copy/paste files and folders or have some of the features listed in Input Director, but it’s rock-solid on reliability. The nice thing about synergy is that it’s platform-independent. You can share the keyboard, mouse, and clipboard on a Windows machine with that of a Linux or Mac, and you can add as many machines to the config as you like.