Quick answer: Use 64-bit Windows if you have 2GB or more memory in your computer.

Some of the most common questions I get from readers involve the differences between 32-bit and 64-bit Windows Vista or Windows 7. Here are some articles I wrote in the past on this topic:

• Should I install 32-bit or 64-bit Windows Vista?

• Maximum Memory in 32-bit Windows Vista

• 32-Bit Vista Memory Limits

• Can I run 32-bit programs in 64-bit Windows Vista

In a nutshell, 32-bit Windows can only address 4GB (or less) memory. In the past, I recommended using 32-bit Windows even though 64-bit Windows 7 can address 8GB (in Home Basic), 16GB (in Home Premium), or 192GB (in Enterprise, Business, or Ultimate). The reason: you couldn’t always get drivers for 64-bit Windows.

Good news–in the years since Windows Vista was released, Microsoft has convinced hardware vendors to produce 64-bit drivers for everything. So, unless you have some really old hardware that you’re not willing to upgrade, you shouldn’t have a problem finding 64-bit drivers.

So, I now officially recommend using 64-bit Windows Vista or Windows 7 if you have 2GB or more RAM in your computer.

Unfortunately, you can’t just upgrade. You’ll need to backup all your files, install 64-bit Windows, and then restore all your files. Then, you’ll need to re-install all your applications.