As many said, You can use the psd include here http://bitbucket.org/nathansmith/960-grid-system/downloads/ to align your design in photoshop. Although 960gs is a good start point for most projects but it is not a solid system.
Take a look at the article on tutsplus
Adam Hawkins has a great article that goes through designing a site using 960gs
He also explains the shortfalls of 960gs
read the section “CSS Frameworks Do Not Solve All Your Problems”