Hardware configurations are very different. A big difference stands from 32 or 64 bit version of operating system, because not all programs will work on any version.
32 or 64 bit came from processors's capabilities: 64 bit processors are more advanced because can use more RAM memory. In order to use 64 bit you need to install a Windows 64-bit version.
Suppose you need to install a software and you do not know what version of Windows you are running on your computer: 32 bit or 64 bit.
Windows 7/Vista users
1. Click Start and go to Control Panel
2. Click System (we have added 2 images, depends how icons are set to appear in your Control Panel)