Is the 11.6" 64-bit compatible?

[potentpotable]

I know this is a totally noob question, but I have no idea: when I download and install programs, do I select the 64-bit versions over the 32-bit? Or, for optimal performance, is the 32-bit preferred?

(E.g. Firefox)

 

[pyramid6]

Yes, it is 64bit.

 

[Romulus]

All Apple computers have been 64bit compatible since the release of the Merom C2D processors 4-5 years ago...