End of Year

I need to perform a calculation base on how much savings will be actualized in the current year based upon a start date for a project. I need the calculation to be dynamic as the start dates vary from project to project.

For instance, Project 1 start date is May 5, 2010 and will save $500,000 over 36 months. Project 2 start date is July 27, 2010 and will save $1,300,000 over 48 months.

I need to calculate the dollar amount saved from Project 1 for 8 months in this year and Project 2 for 6 months in this year. Plus I will calculate how much was saved over full years through the partial year on the other end.

Anyone out there have any advice on how to do this?