Windows:  Desktop

Make the background of desktop icons transparent (XP)

Control Panel > System > Advanced > {Performance} Settings.
On the Visual Effects tab, check Use drop shadows for icon labels on the desktop.

Restore My Documents folder if deleted (98)

To restore My Documents to the Desktop, click Start, then Run, and type:rundll32 mydocs.dll, RestoreMyDocsFolder

Remove shortcut icon arrows

Go to [HKEY_CLASSES_ROOT\LNKFILE], and delete IsShortcut
Go to [HKEY_CLASSES_ROOT\PIFFILE], and delete IsShortcut

Change My Computer's Icon

Windows 98: Control Panel > Display > Appearance
Windows XP: Control Panel > Display > Desktop > Customize Desktop

Hide Icon
Hide all Desktop icons (9x/XP)

HKEY_CURRENT_USER\ Software\Microsoft\ Windows\CurrentVersion\ Policies\Explorer
NoDesktop (DWORD value):
Set to 1 to hide all icons.
Delete NoDesktop to undo.
Hit F5 to refresh the desktop.
Hide Network Neighborhood, My Network Places (9x)
Run Poledit.exe (You may have to install it: It is on your Windows CD in\tools\reskit\netadmin\poledit).
File > Open Registry > (double click) Local User > Shell > Restrictions
Check Hide Network Neighborhood or/and My Network Places
OK > File > Save
Reboot.

Hide My Documents, My Computer, My Network Places, Internet Explorer (XP)

Right-click on the desktop, then click Properties > Desktop > Customize Desktop

Hide My Computer (9x/XP)

Create a transparent icon or create a bmp file that consists of a single pixel.
In Display properties effects, change the My Computer icon to point at your new icon.
Rename My Computer to one space.

Add and remove item types from the New Menu
Add Item Types

When you right-click on your desktop, there is a New submenu that contains a list of templates. A template is visible if the related entry in the [HKEY_CLASSES_ROOT] hive associated with a file extension has a sub-key called ShellNew.
For example, on the New submenu there is an entry for Text Document. This entry is visible because of the key [HKEY_CLASSES_ROOT\.txt\ShellNew]. Create a blank document of the corresponding application, and put it into the Windows\ShellNew Folder. Go to that file type under [HKEY_CLASSES_ROOT], create a subkey named ShellNew and create the string-value File Name in it. Change this string's value to the blank document's filename.

Ex: [HKEY_CLASSES_ROOT\ .wav\ShellNew\FileName], and FileName's value = "sndrec.wav".

Remove Item Types

Read Add Item Types, and delete or rename the subkey named ShellNew. Hit F5 to update the items in the New submenu.

Save color scheme

Export [HKEY_USERS\.DEFAULT\ Control Panel\Appearance\ Schemes\{Name of Scheme}]

Create tool tips for desktop icons.

Search the registry for keys with the name Info Tip. You may replace the descriptions and you may add Info Tip keys for other Class-IDs.

Create a button to Reboot Windows XP

To create a reboot icon on your desktop: Right click on an open area of the desktop Select New/Shortcut Enter in "shutdown -r -t 00" - no quotes Press Next For the name, enter Reboot or anything you like.
Click Finish.

Remove Shortcut arrow from Desktop icons

Here's how you can remove those shortcut arrows from your desktop icons in Windows XP. Start regedit. Navigate to HKEY_CLASSES_ROOTlnkfile Delete the IsShortcut registry value. You may need to restart Windows XP.

Performance Increase through My Computer

Start > Right Click on My Computer and select properties.
Click on the "Advanced" tab
See the "Performance" section? Click "Settings"  Disable all or some of the following:
Fade or slide menus into view
Fade or slide ToolTips into view
Fade out menu items after clicking
Show Shadows under menus
Slide open combo boxes
Slide taskbar buttons
Use a background image for each folder type
Use common tasks in folders

Change Briefcase icon on NT/W2K/XP

You can change the Briefcase icon and replace it with an icon of a metal attach?case using the following Windows
NT/W2K/XP registry hack:
Hive: HKEY_CLASSES_ROOT
Key: CLSID\{85BBD0920-42A0-1069-A2E4-08002B30309D}
Name: DefaultIcon
Type: REG_EXPAND_SZ
Value: %SystemRoot%\system32\syncui.dll,1  (shiny metal attach?icon)
Value: %SystemRoot%\system32\syncui.dll,0  (default leather Briefcase icon)
Download these registry files already made:
Leather.reg
MetalAttache.reg
After changing to the icon, you may have to log off then log back on or restart your computer for the change to take effect.

Create a Lock Computer Shortcut Icon

1. Right click on the desktop, select New > Shortcut.
2. Enter rundll32.exe user32.dll,LockWorkStation as the shortcut.
3. Name it Lock Computer.
4. Right click and choose Properties.
5. Click on "Change Icon"
6. Search through shell32.dll in the System32 directory and find an appropriate lock icon.
NOTE: This effectively dumps you back to the "Welcome" log on screen. Of course this will only work if you have entered a password for your profile.
ADDENDUM: If you want added security, go to the Control Panel and click on "User Accounts". Click "Change the way users log on or off", and deselect the "Use the Welcome Screen" option.This will switch Windows back to the classic log in box.