Mail merge data and graphs into a letter

I am trying to do a benefit statement for our employees. I need to find a program that will merge the data for each individual into a letter and also set it up somehow so that I can merge a graph into the letter that will be specific to each individual’s information. I have Office 2007, but I can not merge a graph. Is there a simple to use software program that will do this for me? We will be doing a very large number of these letters so going through each one and making the graph after the data has been merged is not an option.