Can someone provide a list or link of what Add-ins currently WILL and WILL NOT work with Excel 64bit Excel 2010. I have both Office 2010 & Office 2013 installed --- I was planning to update my Office 2010 to 64 Bit , and keep Office 2013 as 32 bit because of issues with add-ins and its what I primarily use. I really only need 64 Bit to work with potentially large Excel files and to work with PowerPivot / DAX. Someone has told me its possible to run 32 bit office and 64 bit office if versions are different (ie. 14 & 15 / 2010 & 2013). Based on my scenario - it seems the best option is to update my office 2010 to 64 bit because I plan to only use for Excel and possibly Access --- any thoughts / comments or suggestions are appreciated. Thanks