In Microsoft Project, you can assign budget and cost resources to account for project expenses related to non-labor and non-material items such as resource travel and per diem costs or licensing. These budget and cost resources, when assigned to the project, are assigned at the project summary task level. This way, they apply to the entire project.
The great thing about these budget and cost resources is that, when assigned, they don't have any impact on your project schedule. In Project, when you modify a resource assignment for any task, due dates and other task dependency relationships update, as well. This is one of the major selling points of Microsoft Project - resource-driven scheduling.
But, when you denote a resource as a "cost" or "budget" resource, when assigned, these resources do not impact your overall project schedule. You can learn how to create a budget and apply it to a Microsoft Project 2007 plan here.