Compiling XML spreadsheet data (do I need a program?)

[knotworking]

Dipping my big toe into the XML water, I've created an XML spreadsheet in excel. The sheet will be used by employees to enter various data in various cells.

Some cells will only contain numbers, others text descriptions and unformatted data. I will end up having several hundred individual sheets from the employees.

Is there a way to pull particular data cells from all the sheets into one master sheet that totals or otherwise breaks down the information into one file? I know there are several pay programs like Crystal Reports that probably do what I want but, I'd like to be able to compile the data on my own (if it's reasonably possible).

Anybody experienced in XML know if this is possible (and explainable)?

THANKS!