Recommended way to write/export excel files?

i'm sure that there are many ways to write and export excel files

including using the COM class, and the Spreadsheet_Excel_Writer package from PEAR.

Thus i was wondering which is the recommended way to do it? I don't want to have extra installions to support the method. like the OLE dependency from the Spreadsheet_Excel_Writer from PEAR.

What I want to do is to write and save the excel file to the server and then attach them to a email

or write to a excel filehandler and then attach the filehandler as an excel file to the email without saving it.

I don't want to have a dialog popup to let the user save the excel sheet.

I'm not afriad of looking into and learning complicated code. If anyone can point me in the right direction or show me a tutorial, I would be really greatful