All spreadsheets in the Censustools collection were created with Microsoft Excel 97. A version of MS Excel, version 97 or newer is required to open and use the spreadsheets. MS Excel is a separate software program and is NOT INCLUDED in the Censustools CD.
Other spreadsheet programs may open the Censustools files, but I cannot vouch for their ability to properly display them.
The PDF versions of the spreadsheets require Adobe Reader, available as a free download from the Adobe website.