Not sure what it is like in Windows 8 but in windows 7
Right click on COMPUTER icon on desktop
Select PROPERTIES
It should show what type it is on the screen that comes up- under SYSTEM-->System Type.
Ahh.. google helped
1. Open Windows 8 Control Panel
2. Touch or click on System and Security
3. With the System and Security window now open, click or touch System
4. With the System applet now open, titled View basic information about your computer, find the System area, located under the large Windows 8 logo. It will say either 32 bit or 64 bit there.
another good info-
How to Determine What Version of Windows You Have Installed