Assigning variable data to a drop down list

I have a job-cost workbook with a number of worksheets in it that allow us to cost a renovation job from start to finish. One of the sheets is a change order page where we add items, as the project progresses, that were not part of the original costing. The way our workbook is setup is that the costing is broken down into a number of categories to allow us to more precisely analyze the data. On my change order sheet I have a drop down list to be able to select one of the categories available, and then the columns beside that selection have cells that we would enter in the corresponding costing depending on the item. I want to be able to apply that costing to my summary page based on the category that was selected from the drop down list. How do I assign the cell values to that particular category selection and reference that to my summary sheet?

ben_hensel - If I could reach through the screen and shake your hand, I would! Thank you so much!! Given this was my first post on this forum, I am quite glad I signed up!