In Re: Help in OLE perl, afoken indicates that you can't interact with the desktop via the web server. This means you can't start Excel, which would create a window in the desktop.

Regards,

John Davies

Update: my spies tell me that SharePoint may be a way forward, but I don't know it (see http://office.microsoft.com/en-us/sharepoint-server-help/introduction-to-excel-services-and-excel-web-access-HA010105476.aspx). Another option I don't know much about might be a cloud service such as Office365.