Very interesting and helpful article. I love the open source and free availability to the DLL you provided. That said, we do a lot of advanced Excel manipulation at our location and have nothing but good things to say about SoftArtisans OfficeWriter ExcelWriter product (http://www.officewriter.com). Yes, it is expensive, but is VERY well supported and can do just about anything you want to do without having Excel actually installed. We do a TON with this product and have used it since it's ActiveX version. No, I don't sell it or get kick-backs. 😀

Haven't used WordWriter or any of their other products due to lack of need, but if you are in a nasty bind, this is a solid solution.