What is the best way to clean a Macbook?

My Macbook is starting to look less-than-white. I love the white, so you can see how this is mildly depressing. I have heard that there are some chemicals (including ordinary soaps) that mar the look of the plastic, so I would rather not jump headlong into a belated spring cleaning project.

Does anyone know of a safe, effective way to clean the exterior of the machine. I’m looking for something that will make it look brand new.

The screen could also use some work: With the screen off, you can see the outlines of some of the keys. What are safe, effective screen-cleaning techniques?

Again, I am looking for the brand-new look; I am also not afraid to put a little elbow grease into this. I just need to know what cleaners to use (safely).