Red Gate software has been worth every penny for us when trying to do what you are wanting...

http://www.red-gate.com/products/index.htm


>can have snap shot of database offline & sync it back to maindata. What I want is to take a snap shot of data on my laptop so that I can work on it at night and sync changes made with the original data (the main data will also be changed in the night).
>
>Rajesh