Excel.Application instance

Sep 18 2011 8:17 AM

Hi.
I am creating a program that gets data from a excel file and writes multiple results in several excel files for printing.
When I want to write the files, how many Excel.Application instance is necessary? I mean can I create an instance of Excel.Application for all of the files or I should create Application instance for each of them?
How about Excel.Workbook?

Thanks