Well, if you want to create an Excel file (either CSV or XLS), you can either create an archive of the files you are creating (depending on the type fo application you are building, or the client's requirements for the application), or have the file dynamically open.
Using the BiffWriter classes quoted above, the .XLS file opens dynamically without the need to save the file. Place the files from the phpclasses.org site into a directory, so your PHP code can reference them easily. An example of how to build the code up is supplied with the download from phpclasses.org.
In answer to your question, certainly with regards to the BiffWriter classes (and probably with the COM classes), the export button will lead to the code that dynamically creates your Excel file. The Excel file will open in a separate window - if the user has Excel installed in their machine, Excel will open.
