Software: Sysinternals Free Utilities

Personally I am not a huge fan of using 3rd party utilities for performing most types of systems diagnostics. I like to rely on the OS's built-in tools as much as possible.  Primarily I don't want to be reliant on a utility that I might not have with me at the time or it requires some type of installation on a customer's system.

Although when I do have to rely on external utilities, one of the first sites I use is Sysinternals (http://www.sysinternals.com). These are some of the better diagnostic and troubleshooting utilities available for Windows. Also, Mark Russinovich and his team are continuously updating the existing tools and creating new ones.

Besides being free and powerful tools, all (or most) of these utilities don't require that they be installed (this is known as being a 'portable application' because it can be moved between systems without installing it).

Sysinternals Suite

The tools on the site can be downloaded individually, or you can download the Sysinternals Suite which contains the latest versions of all the utilities in one package.  As of the writing of this article, below is a current list of the programs that come included within the suite (see below).