We have a lot of spreadsheets (xls) in our source code repository. These are usually edited with gnumeric or openoffice.org, and are mostly used to populate databases for u
Quick and easy with no external tools, works well as long as the two sheets you are comparing are similar:
=if(Sheet1!A1 <> Sheet2!A1, "X", "") in the top left cell (or equivalent: click on the actual cells to automatically have the references inserted into the formula)If the sheets are similar, this spreadsheet will be empty except for a few cells with X in them, highlighting the differences. Unzoom to 40% to quickly see what is different.