Also be aware that Office 2010 comes as 32-bit or 64-bit, first version to be that way.
If using the 64-bit version on 64-bit Windows you have to first uninstall/remove all of the 32-bit version and the separate installs of the Viewers [Word, Excel, PowerPoint] and the Compatibility Pack/File Converter [which have been/are being discontinued].
The Compatibility Pack is needed by Office 2000 through Office 2003 for compatibility with Office 2007 and later file formats.
To eliminate confusion, Microsoft Office may be included with a Windows computer but is a separate program, not actually needed for running Windows.