Since drivers operate between the hardware and the operating system, it isn’t possible to install 32-bit drivers on a 64-bit operating system, even though you can run almost all 32-bit applications on your 64-bit Windows. Hence, the first step in your 64-bit deliberations is a careful check of whether all required drivers are available as 64-bit versions. If you’re willing to spend some time and give x64 Windows a try, you may consider installing a 64-bit Vista version just for fun—there is a 30 day trial period that allows you to play around with the system and look at the driver support before you actually have to activate your copy.
XP and Vista
While it is usually possible to use many Windows XP drivers on Windows Vista, this doesn’t apply to 64-bit driver versions. A 32-bit Windows XP driver for an audio device or game controller will most likely work on Vista-32. However, there are no exceptions for Vista x64 and its required drivers, as Vista will not install any driver that isn’t correctly signed.
You don’t necessarily need chipset drivers or graphics drivers if your graphics adapter is already a few years old. In this case, Windows Vista x64 will support all of them with built-in drivers, even if at slightly reduced performance levels. AMD and Intel typically are quick with releasing platform drivers for important operating systems, and even AMD/ATI and Nvidia have been making sure that all relevant Radeon and GeForce cards are properly supported. This is mostly done via the unified driver concept, which crams lots of individual driver packages into one archive, inflating the download.
It is more difficult to find drivers for non-standard components, especially peripherals. Every printer, scanner, card reader, mouse, keyboard, and communication device is a potential incompatibility risk if it is at least 18 months old. Be ready to search in vain if your peripherals are several years old, even if they were made by huge brands such as Brother, Canon, HP, Samsung, and others, just to name a few. There are no exceptions; popular brands simply don’t guarantee availability of 64-bit drivers.
Microsoft offers a Windows compatibility page to research driver availability: http://www.microsoft.com/windows/compatibility/default.aspx