I have two related (I think) questions so please bare with me.

I picked up InfoPath and encountered XML for the first time about a week ago
and have been given the task of making InfoPath forms sourced from an Excel
spreadsheet.  I am quite perplexed about how to get my Excel spreadsheet to
be an XML Schema.  MS InfoPath online training courses showed me that XML
Schema columns should display in a nice "table and column" expandable format
within the Data Source task pane.  Mine don't.

I save a sample XLS as an XML and then open the XML as a data source.  
Instead of what I expected - Named Range or Sheet Name as "table" and the
content of Cells A1 and A2 as "Columns" - I get something like this:
-Workbook
+o:DocumentProperties
+x:ExcelWorkbook
+Styles
+Worksheet
No sign of anything I recognise from the content of the spreadsheet, no
matter how deep I drill into the expandables.

I read that an XML Schema is just an XML renamed XSD, so I tried that too,
with the same result.  I tried using XL2002 and XL2003 to convert to XML/XSD,
same result again.  Can anyone help?

I don't really want to have to convert my XLS file into an XML file anyway,
my ideal would be to leave my XLS intact, attach an XML Schema to it and then
build my InfoPath forms from there.  Does anyone know if this is possible?  
If so, how?

Thanks in anticipation
Sara