I am currently running Windows Vista Home Premium 64-bit on my home computer, and am considering installing Windows 7. I use this computer in a home/office environment which does not require extreme precision, large databases, encryption or high security for which a 64-bit system may be preferred. Connected to the computer are also scanners, cameras, and printers some which are 7 years old and for which printer drivers or twain drivers may not be available in 64-bit versions. I assume 64-bit data files require more storage space than comparable 32-bit versions and that processing takes longer for 64-bit operations than for similar 32-bit operations. I believe I need only to install a 32-bit version of Windows 7 as I can’t see the point of a 64-bit version in my case. Is there any practical reason why the 64-bit version is to be preferred?

This is a very good question which I am glad that you asked, since many other people have asked me this question in the past. However, before we commence, for those who are not familiar with 32-bit and 64-bit operating systems this refers to the amount of information which the processor in the computer can handle at one time. We could go into technical explanations, but that is not really necessary for our purposes (if you are interested then I would encourage you to read the Wikipedia article on 64-bit computing at en.wikipedia.org/wiki/64-bit). However, for the purpose of our discussion you just need to accept that 64-bit capable CPUs can handle data which is 64-bits in length at one time, in contrast with 32-bit CPUs which can only handle 32-bits of data at once. In summary, this means that the CPU can process more data at one time.

Many users immediately think that purchasing a 64-bit capable computer will provide performance increases. However, this is not generally the case. In order to take advantage of 64-bit processing you need to be running a 64-bit capable operating system. Windows comes in both 32 and 64-bit variants, as you may discover if you purchase Windows Vista and find that it comes with both 32-bit and 64-bit DVDs. Additionally, the applications which you are running on the computer also need to support 64-bit processing. 32-bit applications will generally run without issue (I say generally, because some may encounter problems but the majority should be fine) but they will not take advantage of the increased processing performance which 64-bit offers.

In addition to the potential performance increases, if you have more than 3 GB of memory in the computer then you will generally need a 64-bit operating system in order to access and address all of the memory. This is known as the 3 GB barrier (en.wikipedia.org/wiki/3_GB_barrier) which refers to the limitation of some 32 bit operating systems to use more than 3 GB of memory. Depending on the version of Windows being used, this is generally around the 3.2 – 4.0 GB mark, meaning that the operating system can only address and use that approximate amount of system memory but will not be able to use any more above that amount. As such, if your computer has 4 GB or more RAM then you will need a 64-bit operating system to fully access this memory. An interesting article available on the Microsoft website details the memory limits for all the Windows releases (msdn.microsoft.com/en-us/library/aa366778(VS.85).aspx). As you will see, all 32-bit releases of Windows (up to and including Windows 7) support a maximum of 4 GB of physical memory whereas 64-bit editions can support far greater amounts. Given that most computers these days come standard with 4 GB of RAM (and the demand for more RAM in computers will only become greater in the future) installing a 64-bit operating system provides for a good degree of future proofing.

So to answer your specific questions regarding 64-bit systems, 64-bit data files do not require more space on the hard drive to store the data. This is because 64-bit refers to the amount of memory which the processor in the computer is able to address at once. As we previously discussed, this means that the CPU can handle more data at once making the processing (in theory) more efficient. The number of bits which the CPU can process is not related to storage. As an example, there is no difference between a Word document on a 64-bit system and 32-bit system (otherwise a Word document created on a 64-bit system would not be able to open on a 32-bit system) – it just means that, assuming the program used to read the Word document is 64-bit compatible and so is the operating system, that the CPU could process more of that file at once. That said, you may find that 64-bit programs are larger to install than 32-bit programs. Of course, this could also be the other way around – 64-bit programs may be smaller to install than 32-bit programs. This is completely dependent on how the program has been written. To address your second question, processing should be more efficient on 64-bit systems given that more data can be processed at once. However, this depends on whether the application itself has been optimised and written for 64-bit systems.

Your question does raise a very good point regarding device drivers, as drivers written for 32-bit systems will not work on a 64-bit system. Therefore, if you have older devices which may not have updated drivers for 64-bit systems then you may be unable to use those devices on a 64-bit system. That said, it is likely that if the device is so old that there are no 64-bit drivers it may also not have drivers which support Windows 7, so you may not be able to use the device on Windows 7 at all. However, you should definitely double-check whether the devices on your computer are compatible before taking the leap to a 64-bit operating system.

Additionally, as previously mentioned, there may also be applications which do not support a 64-bit operating system and will not work. Therefore, you should also check applications (in particular, older applications) to ensure that they will continue to work.

To summarise, I am of the opinion that unless you have a good reason not to run a 64-bit operating system (such as legacy devices which do not have drivers available, or old incompatible applications) you should install a 64-bit operating system on your computer. This is going to be the standard operating system option in the future, and it provides the most flexibility for hardware changes (such as operating with more than 4 GB of RAM) in the future.