This code creates an Excel-window where you can use the all the Excel-abilities!

Along the lines of what dragonchild pointed out, that code does not really create an Excel window at all. It returns Excel data to the client, but it's the client's duty to handle it correctly by, for example, opening it in an Excel window. Under normal circumstances, this task is beyond the scope of the Perl script. The client must be configured correctly ( ie Excel is installed properly ) for this to work as expected.