Despite the performance benefits, the recommendation to download and install the 64-bit version over the 32-bit version was not straightforward. Microsoft itself issued specific guidance that often advised against the 64-bit installation for general use.
You cannot mix 32-bit and 64-bit Office applications on the same machine. How to Download Office 2010 64-Bit Legally office 2010 64 bit download
Crucial for files exceeding 2 gigabytes (GB) of RAM. Despite the performance benefits