There is an example that ships with LabVIEW that shows how to call a macro in Excel. It is called Excel Macro Example.vi. There are also quite a few discussion forum threads on calling into Excel.
The Report Generation Toolkit also provides a lot of functionality for controlling Excel from LabVIEW.
Doug M Applications Engineer National Instruments For those unfamiliar with NBC's The Office, my icon is NOT a picture of me 🙂