What is the difference between 32-bit and 64-bit versions of Windows?
The terms 32-bit and 64-bit refer to the way a computer’s processor (also called a CPU), handles information.
The 64-bit versions of Windows can utilize more memory than 32-bit versions of Windows. This helps minimize the time spent swapping processes in and out of memory by storing more of those processes in Random access memory (RAM) rather than on the hard disk. This, in turn, can increase overall program performance. For more details, go to A description of the differences between 32-bit versions of Windows Vista and 64-bit versions of Windows Vista online.
How can I tell if my computer is running a 32-bit or a 64-bit version of Windows?
To see if your computer is running 32-bit or 64-bit Windows, do the following:
1. Open System by clicking the Start button 
2. Under System, you can view the system type.
Can my computer run a 64-bit version of Windows?
To run a 64-bit version of Windows, your computer must have a 64-bit processor. To take advantage of the additional capability to utilize memory on 64-bit versions of Windows Vista, you should have at least 4 GB of RAM installed on your computer.
Additionally, you will need to make sure that you have 64-bit drivers for your hardware and that your programs will run in a 64-bit Windows environment. Device drivers that are 32-bit do not work on computers running 64-bit versions of Windows. If you are trying to install hardware that only has 32-bit drivers available, that hardware will not work correctly on 64-bit versions of Windows. Also, programs that try to install 32-bit device drivers on 64-bit versions of Windows will encounter errors. For information about updating drivers and troubleshooting issues with device drivers for 64-bit versions of Windows, contact the manufacturer of the hardware or software.
To find your computer’s processor speed, do the following:
1. Open System by clicking the Start button
2. Under System, you can view the processor type and speed.
Can I upgrade from a 32-bit version of Windows to a 64-bit version of Windows?
No. If you are currently running a 32-bit version of Windows, you can only perform an upgrade to another 32-bit version of Windows. Similarly, if you are running a 64-bit version of Windows Vista, you can only perform an upgrade to another 64-bit version of Windows Vista.
For detailed information about installing and upgrading 32-bit and 64-bit versions of Windows, go to Installation choices for Windows Vista (32-bit) or Installation choices for Windows Vista (64-bit) online.
If you want to move from a 32-bit version of Windows to a 64-bit version of Windows Vista, back up your files and perform a clean installation of the 64-bit version of Windows Vista.
Can I run 32-bit programs on a 64-bit computer?
Many programs designed for a computer running a 32-bit version of Windows will work on a computer running 64-bit versions of Windows without any changes. However, in some cases there might be differences in performance. If a 32-bit program uses embedded drivers, the drivers might not work in the 64-bit environment. If you have a 64-bit computer, it’s best to run programs designed to run on a 64-bit computer.
Would I benefit from using a 64-bit computer?
Yes. A 64-bit computer can process twice as much information as a 32-bit computer, and can have significantly more random access memory (RAM). The 64-bit versions of Windows Vista on computers with at least 4 gigabytes (GB) of RAM can be more responsive when you are running many programs at once. They are usually compatible with hardware devices and programs you might currently be using, and can help ready your computer for the next generation of performance improvements. This makes a 64-bit computer a good choice whether you’re editing family photos and video, playing games, or using other programs that require complex calculations and a lot of memory, such as Computer Aided Design (CAD) software. A 32-bit computer still works very well for most programs, however. For example, spreadsheet programs, web browsers, and word processing programs will run at about the same speed on either a 32-bit or a 64-bit computer. For more information about the benefits of running 64-bit computers, see Understanding 64-bit PCs online. Programs running on 64-bit versions of Windows Vista perform better if both hardware drivers and 64-bit programs are available.
If I’m running a 64-bit version of Windows, do I need 64-bit drivers for my devices?
Yes, all hardware devices need 64-bit drivers to work on a 64-bit version of Windows. To learn how to check for drivers for hardware that isn’t working properly or go to the device manufacturer’s website. You can also get information about drivers by going to the Windows Vista Upgrade Advisor website.
Additionally, some 32-bit programs might use embedded 32-bit drivers, which might make the programs work improperly.
Soji Adeyanju 
Hi,
I am using an Windows Vista 64 Bit version. I want to install windows XP 32 Bit version on this laptop. Is that possible?
Regards,
Marcel