How can you backup and restore the windows Registry?

Windows 95
Microsoft included a service on the Windows 95 CD-ROM that lets you create backupes of the Registry on your computer. The Microsoft Configuration Backup program, CFGBACK.EXE, can be found in the \Other\Misc\Cfgback directory on the Windows 95 CD-ROM. This utility lets you create up to nine different backup copies of the Registry, which it stores, with the extension RBK, in your \Windows directory. If your system is set up for multiple users, CFGBACK.EXE won't back up the USER.DAT file.
After you have backed up your Registry, you can copy the RBK file onto a floppy disk for safekeeping. However, to restore from a backup, the RBK file must reside in the \Windows directory. Windows 95 stores the backups in compressed form, which you can then restore only by using the CFGBACK.EXE utility.

Windows 98
Microsoft Windows 98 automatically creates a backup copy of the registry every time Windows starts, in addition to this you can manually create a backup using the Registry Checker utility by running SCANREGW.EXE from Start | Run menu.
What to do if you get a Corrupted Registry
Windows 95, 98 and NT all have a simple registry backup mechanism that is quite reliable, although you should never simply rely on it, remember to always make a backup first!

Windows 95
In the Windows directory there are several hidden files, four of these will be SYSTEM.DAT & USER.DAT, your current registry, and SYSTEM.DA0 & USER.DA0, a backup of your registry. Windows 9x has a nice reature in that every time it appears to start successfully it will copy the registry over these backup files, so just in case something goes wrong can can restore it to a known good state. To restore the registry follow these instruction:
1. Click the Start button, and then click Shut Down.
2. Click Restart The Computer In MS-DOS Mode, then click Yes.
3. Change to your Windows directory. For example, if your Windows directory is c:\windows, you would type the following:
cd c:\windows
4. Type the following commands, pressing ENTER after each one. (Note that SYSTEM.DA0 and USER.DA0 contain the number zero.)
atttrib -h -r -s system.dat
atttrib -h -r -s system.da0
copy system.da0 system.dat
atttrib -h -r -s user.dat
atttrib -h -r -s user.da0
copy user.da0 user.dat

source:
http://www.pctools.com/guides/article/id/1/page/5/

Registry Hack : Load Application Faster

We start with a simple hack .Type "regedit" in the Run Command Box from Start Menu.This hack will load applications faster.The Windows prefetcher aims to load applications faster bt "prefetching" the application and storing it in the pre-fetch cache.You can speed up the application loading by changing the default value of one the settings under the relevant key.

Navigate to :

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\Memory Management\PrefetchParameters

The default value of the EnablePrefetcher setting is 3.Change this value to 5 to make application load faster.You can also experiment with higher values upto 9 and can see whether you get any improvement or not.

Windows Registry : Introduction and Structure

The Windows registry is a directory which stores settings and options for the operating system for Microsoft Windows 32-bit versions, 64-bit versions and Windows Mobile. It contains information and settings for all the hardware, operating system software, most non-operating system software, users, preferences of the PC, etc. Whenever a user makes changes to Control Panel settings, file associations, system policies, or installed software, the changes are reflected and stored in the registry.

Structure

Keys and Values

The registry contains two basic kinds of elements: keys and values.

Registry Keys are similar to folders - in addition to values, each key can contain subkeys, which may contain further subkeys, and so on. Keys are referenced with a syntax similar to Windows' path names, using backslashes to indicate levels of hierarchy. E.g.

HKEY_LOCAL_MACHINE\Software\Microsoft\Windows refers to the subkey "Windows" of the subkey "Microsoft" of the subkey "Software" of the HKEY_LOCAL_MACHINE key.

Registry Values are name/data pairs stored within keys. Values are referenced separately from keys. Value names can contain backslashes which would lead to ambiguities were they referred to like paths. The Windows API functions that query and manipulate registry values take value names separately from the key path and/or handle that identifies the parent key.

Hives

HKEY_CLASSES_ROOT

Abbreviated HKCR, HKEY_CLASSES_ROOT stores information about registered applications, such as Associations from File Extensions and OLE Object Class IDs tying them to the applications used to handle these items.

HKEY_CURRENT_USER

Abbreviated HKCU, HKEY_CURRENT_USER stores settings that are specific to the currently logged-in user.

HKEY_LOCAL_MACHINE

Abbreviated HKLM, HKEY_LOCAL_MACHINE stores settings that are general to all users on the computer.

HKEY_USERS

Abbreviated HKU, HKEY_USERS contains subkeys corresponding to the HKEY_CURRENT_USER keys for each user registered on the machine.

HKEY_CURRENT_CONFIG

Abbreviated HKCC, HKEY_CURRENT_CONFIG contains information gathered at runtime; information stored in this key is not permanently stored on disk, but rather regenerated at boot time.

HKEY_PERFORMANCE_DATA

This key provides runtime information into performance data provided by either the NT kernel itself or other programs that provide performance data.

[Wikipedia]

Customizing Windows XP

Clean the Start Menu

The Windows XP Start menu is "polluted" with a number of extra links courtesy of Microsoft. At the top there are links to the Internet and E-mail programs; these default to the Microsoft programs. We'll discuss changing those later.

It is, however, easy enough to remove a program from this list: just right-click on the program you want to remove, and from the menu select Remove from This List. 

When you right-click, you might also note that Pin to Start menu is an option. 

When you select that option, the shortcut will be moved to the top of the Start menu, directly below the E-mail link. 

You can also remove a program that was pinned to the Start menu by right-clicking, and choosing Unpin from Start menu (which will restore it to its position on the lower part of the start menu), or choosing Remove from This List, which will remove it completely from the Start menu.

Next you will notice a great number of links on the right side of the Start menu such as My Documents, My Recent Documents, My Pictures and My Music.

Well, I don't know about you, but that's nothing that I need there! Just right-click an empty space on the Start menu, click Properties, click Customize and select the Advanced tab.

Now you can customize the look & feel of your Start menu in whatever way you want! There are a number of items (Control Panel, My Computer, My Documents, My Music, and My Pictures) for which you have these three options:

• Display as link
• Display as menu
• Don't display this item

It is especially useful to have the Control Panel as menu, as this will create faster access to the individual Control Panel applets.

There are another number of options... I suggest you check it out.

One other option I should mention is the Highlight newly installed programs. 

This is another annoyance you will want to switch off quickly! Not only will newly installed programs be listed with a yellowish highlight in the All Programs menu, you will also receive a pop-up when you open the start menu that tells you New programs installed.

On the General tab (after pressing Customize on the Taskbar and Start Menu properties), you can also change the Internet & E-mail programs listed on the Start menu. 

The drop-down boxes should contain all programs installed on your system.

Also you can change the number of shortcuts listed on the (left side) Start menu, as well as clear the whole list of programs in one shot.

On the Taskbar and Start Menu properties itself, you can also choose Classic Start menu. Choosing this option will make your start menu look like the Windows 2000 Start menu.

Removing "Set Program Access and Defaults"

To reverse the effect, either delete the values you added, or change the Value Data from 1 to 0.

1. Start the Registry Editor
2. Go to HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Policies \ Explorer
3. From the Edit menu select New > DWORD value
4. Enter the name NoSMConfigurePrograms, double-click the new value, and enter 1 as the Value Data
5. Close the registry editor and log off from Windows for the changes to take effect

To remove the icon from the Add or Remove Programs applet in the Control Panel:

1. Start the Registry Editor
2. Go to HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Policies \ Uninstall
3. From the Edit menu select New > DWORD value
4. Enter the name NoChooseProgramsPage, double-click the new value, and enter 1 as the Value Data
5. Close the registry editor and log off from Windows for the changes to take effect