...a term which expresses commitment to educate each child, to the maximum extent appropriate, in the school and classroom he or she would otherwise attend. It involves bringing the support services to the child (rather than moving the child to the services) and requires only that the child will benefit from being in the class (rather than having to keep up with the other students).
Furthermore, they describe a self contained classroom environment as:
...a self-contained classroom means that your child will be removed from the general school population for all academic subjects to work in a small controlled setting with a special-education teacher. Students in a self-contained class may be working at all different academic levels, with different textbooks and different curricula. Self-contained classes offer structure, routine, and appropriate expectations, but some students may require a higher level of specialization.
Here are a few articles relating to both. I hope they help you in making your decision:
For a related article, read Redefining an Integrated Classroom at The East Hampton Star.