Implementing a Responsive Design using CSS Media Queries
Setting up a 960px fixed width grid.
From Fixed grid to fluid grid
Understanding Min-Width vs. Max-Width
The next Video shows a document for helping to understand the differences in the cascade when using min-width versus max-width in a media query. That document is available to download (.pdf). - download Understanding min-width versus max-width diagram.pdf. It can be seen in the image below, and if you click on the image it will bring you to a larger version.
From Fluid to Responsive Design CSS Walk Through