Be careful with add-ins - you need to make sure that they will work with 64-bit Excel if that is what you install.
Microsoft recommended 32-bit Office on 64-bit Windows 7:
http://office.microsoft.com/en-us/w...-version-of-microsoft-office-HA010369476.aspx
I have come across a few problems mentioned on this board that were caused by using Office 2010 64-bit.
Also have a look at Rory's post #11 at:
http://www.mrexcel.com/forum/showthread.php?t=447852