Fred Langa, long time technology writer and contributor at Windows Secrets, wrote about the Windows Registry this month and explained why it needs a routine cleanup.

According to Microsoft, the Windows Registry is a database that stores the information and settings you need to configure your system for one or more users, applications, and hardware devices. Each time you install a new application or a piece of hardware, add a user, or change your PC preferences, the change gets registered in this database. When you uninstall a product all traces of it should be removed from the registry.

Some products handle this well; others leave a mess behind. As Langa says, "Some products leave behind large amounts of digital debris when the software is removed. In fact, this behavior is sometimes intentional; many time-limited software trials, for example, deliberately leave behind special software "flags" that prevent you from using the software after the trial has expired, even if you remove and reinstall the software afresh." He says that software crashes can leave messy registry entries behind, too.

If your PC is relatively new and you haven't added or deleted software or hardware, then you can probably leave the registry alone. But if you're always adding and removing hardware and software, it may be time for a spring registry cleaning. Langa says that "registry bloat" can slow down your PC.

Expert users can edit the Windows Registry using a tool that Microsoft supplies called REGEDIT.EXE—which is sort of like a text editor for the Registry. Making even a tiny mistake while editing your Windows Registry can have disastrous results. For most of us, it's best to stay away from Regedit and manual editing.

Instead, there are a host of registry cleaning tools that make cleaning your registry a bit easier. They'll create a backup of the existing registry, clean the registry of old unused entries, and repair problems. A Registry cleaner will check to see that every program and file referenced in the Registry really exists and is referenced in the proper location so it can be called upon by other programs and files as necessary. So for example, if the registry points to a location of a file that's been moved, the cleaning tool will update the Registry entry with the correct location. If the referenced program or file doesn't exist (say, for example, you uninstalled it), the tool can delete the meaningless Registry entry.

There are dozens of registry cleaning tools on the market. Langa tested a number of them and recommends jv16 PowerTools. Not only does it analyze and flag registry problems, but it tries to automatically fix them. A full-featured 30-day free trial version of the program is available. Langa also likes a free utility, EasyCleaner, though not as much as jv16 PowerTools.

Microsoft's Vista, by the way, works differently. The registry is more locked down and inaccessible to third party applications and hardware. It's a more tamper-proof environment.

The word of the day is CAUTION. You only need to clean out your Windows Registry if you add and remove lots of hardware and software. If you notice that your PC is getting slower and slower, the Windows Registry is often the culprit. But the Windows Registry is like the master bureau of records for your PC and it should be treated with the utmost respect. It takes the form of a hierarchical database with Keys and Sub Keys to keep track of the files. One tiny typo or error and you can really mess up your PC. If you run the cleaner and it reports a lot of problems it might be time to call in a "good geek" who can clean things up for you.