Excel has a lot of formats to save out a table. If you can choose one of these formats then I can give you some help. (If you have to work old excel formats then you are in trouble!) You should save your excel tables to Excel 2002 XML or Excel 2003 XML format. Then you can read/write it with a simple xml parser. (http://en.wikipedia.org/wiki/Microsoft_Office_XML_formats
Here is a refernce to the xml tags: http://msdn.microsoft.com/en-us/library/aa140066%28office.10%29.aspx
If all you want is just a table that has text inside its cells, then dont read the above reference and here is my advice: create a small table (maybe 4x5) and save it as Excel 2002 or 2003 xml. Leave some random cells empty inside your table. Then open the xml file with a text editor/viewer and check out its contents. Most of the tags are just for excel so you can ignore them, you will find out which tags/attributes are important at all. (You can start delete the tags you find unimportant and check if excel can still read the table until you simplified the table to minimal - thats what you will have to save out from your code!) There is only one big mistake you can make, sometimes excel skips some empty columns when it finds some empty cells (this is why you should leave some random cells empty) end then it gives an index to the next nonempty cell in a row without saving the empty cells on the left of it. Thats it!
We use this method to give designers a tool (excel) to tweak the parameters of our program. This solution is so primitive that it can make totally platform independent! Note that you can put in some column/row headers and some coloring for your ppl and your program can ignore those. Later if you have to save space you can trim down the excel file or can convert it to a size optimized custom format.