For those who use Windows, have a desktop and notebook computer and want to use the same keyboard and mouse on both.
Windows has a program called "Mouse without Borders" that let you use the mouse and keyboard of one computer on another like a dual monitor setup. It's works via LAN and I have to say that I haven't any lag. You can copy text from one computer and paste into another and you can drag files too (that are copied to a special folder).

My desktop computer has a big monitor and of course it's better than my notebook and I don't want to spend money in another monitor, so this is a life saver for those who are in the same situation.

Cheers!