How to tell if a computer can install 64 bit OS?

[certforumz]

Programs -> Accessories -> System Tools -> System Information
Look for the System Type

The value of this item will tell you whether your computer is 32-bit or 64-bit:

x86-based PC: It's a 32-bit computer.
x64-based PC: It's a 64-bit computer.

It is the processor and the OS that determine whether the computer runs 32 bit or 64 bit operation. MoBo adapt to these two, usually.