Help woth grids

Well, I am currently working on an application and I want to insert a grid,but which should be unbound.
In fact,I should be able to enter values in the grid rows,giving the user possibility to enter more rows if required.
For example, in an invoicing transaction...where more that one product is being sold,I need to store the information in a grid before saing it to a file.
PLease tell me how to do it,I'm having some problems...also, how do I include a combo box in a grid cell for selection.

Thnx

I am looking for the same thing so if you find anything would you email me at [email protected] and I will do that same.

Thanks