Project Balance and actual cost

Project Balance and actual cost

Hi all
i've a question about projects overview.
In the project list above i have a lot of fields (some of them are empty); my question is is possible to customize a filed for this screen and how.
For example i dont' see a field that is the difference beetween Project Balance and  actual cost that for me is very important. Is possible to create this custom filed (with this simple operation) and where?

Thanks in advance 
Marco