The Role of the Registry in Windows XP

Most hacks and mods you make to your computer fall into one of two categories:

• Programs that you install and run, either continuously (such as antivirus software) or sporadically (such as registration key sniffers).

• Changes to the Registry, either performed manually (which is rarely necessary), using one of the hooks that are built into Windows, or by using a program that knows which Registry entries to hack.

You probably know that the Registry is Windows’ central repository of information.
You may not know that, in fact, the Registry is a horrendous mess, poorly organized (in fact, it’s a stretch to use the terms organized and Registry in the same sentence), sprawling, bloated and . . . well, a lot like Windows XP.

The Registry made its debut in Windows 95 (although there was something called the “Registration Information Editor” in Windows 3.0), and it’s been devolving ever since. Thousands of programmers have stuck their entries in the big database without coordinating among themselves, and it shows.

The Registry’s one great redeeming social value: It’s always there. If a programmer needs to save something so it’ll be around a week or a day or a second from now, the Registry is the obvious place to put it. In addition, many Registry entries are maintained by Windows on the fly, changing to reflect the current operating environment, who’s logged on to the PC, and so on.

The core of the Registry lies in a bunch of files that you can’t edit directly —
Windows won’t let you get into them.

• Default stores settings that are applicable to all users.

• SAM has information from the Security Accounts Manager service.

• SECURITY, as you might imagine, holds security settings. You can’t get
at SAM or SECURITY with Regedit; you have to use Windows’ built-in security programs.

• Software and System hold settings for all of your software, including Windows and other Microsoft software, which end up in the HKEY_LOCAL_MACHINE\SOFTWARE and \SYSTEM Registry keys.

• UserDiff has data that modifies default settings to form the HKEY_CURRENT_USER key.

Don’t be afraid to go into the Registry, but make sure you know what you are going to accomplish before you go in and stick to what you intended to do. Avoid the temptation to poke around and change things just because you think you know what they do.

Or, heck, if you’re like me, you can go in and change things just to see what goes “bump”. . . er, “dump.” I’ve been playing with the Registry for about a decade now, and it’s exceedingly rare to lock up Windows or make changes that can’t be readily undone. Still, if you want to make changes to the Registry that push the envelope, make sure that you have a current System Restore Point.

At the same time, I suggest you avoid Registry cleaners — packages that you buy to scan your Registry and remove entries — like the plague. I talk about them in Chapter 1. I’ve never seen a Registry Cleaner that made a big difference in performance. I’ve seen plenty of screw-ups caused by removed entries that the Cleaner just didn’t understand.