ok so using expression seams more problematic that I thought, so for this iteration I decided to use a simple windows form, this will allow me to think about what elements I want, and how I am going to test this, the aim is to test as close to the interface as possible.

 So here we have come text box’s and a data grid, along with a button, the idea is that the grid is filled from the collection, and the user can enter new transactions using the text box’s and drop down list, when update is pressed any transactions marked for deletion are deleted, and the addition is made.

So the next job is to bind the grid to the collection and get the items to display.