I just wanted to point out that, a couple months ago, I ported the excellent Java library JExcel from Java to native dotNet. I ran into a problem where the 64-bit IIS servers at work did not like the J# (32-bit only) option of compiling JExcel for use with .NET projects. My boss gave me latitude and permitted me the time to do this port.
If you are looking for a convenient way to create Excel spreadsheets or to parse data out of incoming spreadsheets in .NET, let me recommend this product. No, I am not biased. I have used this in its Java incarnation and recompiled with J# for at least 7 years or so and have been impressed with it. The beauty of the library is that Excel does not have to be anywhere near the machine that executes the code to create or read the spreadsheets! Andy Khan, the original developer, did a marvelous job and made many a programmer’s life much easier….
Anyway, the link to the project is: jexcelapi.sourceforge.net and clicking on the Files link will take you to the download area where you can get the Java and C# versions with full source. There is documentation for the Java version which also describes (mostly) the .NET version since the method names are (mostly, with a couple notable exceptions) the same.