On Windows, the webserver service, like almost all other services, is usually not allowed to interact with the desktop (or, in case of Remote Desktop / Terminal Server, any of the remote desktops), and for good reasons. So any program you start from the webserver will hang as soon as it attempts to draw a window. Most likely, you won't be able to use OLE. Try one of the Excel parser modules at CPAN, or even better, put your data into a database.

(Update: See also win32::ole and MS Office 2010 over cgi)

Alexander