Julie, there are two very informative threads about Sensory Integration Disorder (SID) in the General archives. Click on forum home in the upper right hand corner, then select General Archives. Go to page 3 where the threads are.
Get the Out of Sync Child by Carol Kranowitz from the library. When I wasn't sure what was going on with my son, I read it. It wasn't him and he isn't Sensory Integration Disorder (SID), but boy is that one informative book. I recommended it to a friend who read it and now has her 4 year old in a special needs preschool as it fit him to a T.