How do I connect my desktop computer monitor onto my desktop replacement laptop and have it be the default monitor? I am currently using these two as a dual monitor, and have no use for the laptop screen. I want to just close it up, leave it on the side, and pretend I'm just using a desktop computer until my birthday comes and I can get my wonderful Mac Mini.

Please help me.

Usually there is a button you can press on the laptop. It's usually either F4 F5 or F8, but you have to hold down the Function key when you do it. It should have a little picture of a monitor on it, or say CRT/LCD.
http://help.bluebones.net/img/monitor_key.jpg