They say you can tell a lot about a person by the tools they bring to the job. If you're a professional plumber or a carpenter, people will expect you to carry the right tools for the task at hand. The same holds true for IT pros. Those in the know will judge you by the depth and sophistication of the technical toolkit you bring to a support call.

To help you make a good first impression and to cement your reputation as a seasoned troubleshooting guru, I offer the following list of my top 10 must-have Windows utilities for PC support professionals. Some you probably already know. Others you may have heard of only in passing. But all deserve your consideration for a place in your PC support and diagnostics toolkit.

[ Short on time? Take the quick slide show tour: "Top 10 free Windows tools for IT pros, at a glance." ]

1. Sysinternals Suite
When Mark Russinovich and David Solomon embarked on their quest to fill what they perceived to be glaring holes in Windows' management and diagnostic capabilities, they couldn't possibly have known the impact their suite of tools and utilities would have on the greater Windows IT community. Yet here we are, a short decade later, and it's hard to imagine a world without Process Monitor, Autoruns, RootkitRevealer, and the rest of the Sysinternals Suite.

A lot has changed since those early days. Russinovich was eventually courted by Microsoft and now serves as a technical fellow overseeing the evolution of the Windows architecture (much to the benefit of users everywhere). Meanwhile, the Sysinternals Suite has been transformed from unofficial -- yet highly prized and admired -- collection of backdoor hacks into a must-have ensemble of fully sanctioned tools offered under the Microsoft TechNet banner.

There's not much else to say about Sysinternals except that, like all of the tools I've highlighted here, it's absolutely free. And no Windows professional should be without it. For shame!

2. HWiNFO32
What kind of CPU is in the PC you're using? Does it support hardware virtualization so that it can run Virtual Windows XP Mode under Windows 7? How old is the BIOS? Are all of its core hardware components running within normal voltage parameters? Are any components overheating or otherwise misbehaving?