Note: This is NOT the latest release. Look here for the latest release.
This release adds no new features. However, it is the first release that supports Excel 2010.
For Excel 2007 or for Excel 2010 32-bit (even Excel 2010 32-bit on a 64-bit server), use the 32-bit download.
For Excel 2010 64-bit, use the 64-bit download.
Just download and run the EXE. There is no need to uninstall the previous release.