The differences between 32-bit Vista (usually referred to as the x86 version in honor of the 32-bit architecture of Intel’s 80386, 80486, and Pentium processors) and 64-bit Vista are more complex. The good news is that, if you’re buying a new PC with Vista preinstalled, it will probably come with 32-bit or 64-bit processing already enabled, depending on the chipset that powers your machine.

Any new 64-bit PC that’s sold with Vista preinstalled will almost certainly come from the factory with 64-bit drivers and anything else that might be needed to support 64-bit processing.

If you’re buying a retail copy of Vista, and you already own a previous version of Windows, such as XP, don’t buy a full version of Vista. Find out what Microsoft’s current requirements are to qualify for an upgrade version, which is much cheaper. To successfully load an upgrade version, you usually must be installing onto a machine that has the old version installed, or you must have the old version on a CD (which you insert briefly during the installation of the new OS as proof). Microsoft can change these requirements at any time, so confirm this before whipping out your plastic.