Does my computer have 32-bit or 64-bit Operating System (Vista / Windows 7)?

1. Right Click Computer
2. Properties
3. Under "System" see "System type"

Will be "32-bit Operating System" or "64-bit Operating System".

                          OR
Right-clik on the Destop and choose Properties, Then click on
Setting Tab.If color quality Higest(32 bit) then your operating is 32-bit.
and if color quality Higest(64 bit) then your operating is 64-bit.