I am working on some software that uses an OleDB to open a .xls file, query some data, and fill a dataset with the results. I am now looking at using this software on syste
You don't have to have office or the office data connectivity installed, you can use the Jet for OleDB engine which is installed on pretty much every windows machine in existence. However it's very old technology and is limited to 32 bit.
http://msdn.microsoft.com/en-us/library/ms175866.aspx
If you want to avoid this mess entirely then switch over to an app.config file or a properties file and you can get the pure .net solution.
You need either the full Office or the Office Data Connectivity Components installed on the client computers.