Change your Windows XP service pack

You can change your service pack 2 or display service pack 3 or even 4 by just following these steps:
>>Go to start>Run>type regedit to open registry editor(Make a backup of your registry if needed)
>>Navigate to :HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Windows
>>Change the value of CSDVersion from 0x00000200 (SP2) to the Windows XP SP3 value of 0x00000300
>>Reboot and see the change.

Change the default search engine in Internet Explorer

Microsoft has set its default search engine in internet explorer as MSN.Now you can change that search engine to any other you like.
>>Close internet explorer
>>Go to start>Run>type regedit to open registry editor
>>Navigate to following key:HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\SearchUrl
>>Change the value of string key name default to any one of the following values :
>>To specify Metacrawler as the default search page, change the default value to http://www.metacrawler.com/crawler?general=%s
>>To specify AltaVista as the default search page, change the default value to
http://www.altavista.com/cgi-bin/query?q=%s
>>To specify HotBot as the default search page, change the default value to
http://hotbot.com/?MT=%s
>>To specify Google as the default search page, change the default value to
http://www.google.com/keyword/%s

Shutdown or Restart or Logoff your PC at any time

Now you can shutdown your PC at anytime by simply following these small steps:

>>Go to start>Run
>>Type code:at 11:35 shutdown -s to shutdown your PC at 11:35 am
>>To abort type shutdown -a
>>Note all time is in 24 hour format
>>For pm Eg:at 21:30 shutdown -s for 8:30 pm

Also If you want to shutdown your PC in seconds
>>At run type shutdown -s -t 30 to shutdown your PC after 30 seconds

To restart your Pc at any time:
 >>Start > Run
>>Type shutdown -r -t 10 -c "Restarting..."
>>Hit Enter and enjoy !

To logoff:
>>Start>Run
>>Type shutdown -l
>>Hit enter,that's it.

*Note :
-s :: This signify Shutdown Request.
-r :: This signify Restart Request.
-l :: This signify LogOff Request.
-t :: This signify the timer before Restart. (Replace '10' with any number.)
-c :: This signify comment.

*To stop timer Go to Start>Run>Type shutdown -a (abort)

Open command prompt even when it is blocked by admin

Now you can open cmd even when it is blocked by admin.Just follow these steps:
>>Go to Start>All programs>Accessories
>>Open calculator
>>Click Help in the menu and click help topics option
>>When help window opens > Right click on top left corner of that window where you see the symbol  ?
>>And now,click on jump to url and put this : file:///c:/windows/system32/cmd.exe 
>>Now you see that command prompt is opened without admin's permission

Easy way to crash a computer(Infinite way)

This is bad thing to say but any PC can be crashed within a minute by just following these steps:

>>Open notepad type
Start
Start
Start
Start
......8 times
>>Save this file as hax.bat
>>Run it
>>It opens up 8 times
>>Then type hax.bat at last line
>>Now this will open up start for infinite times

Check whether your XP is activated or not

Here's a process to check whether your windows XP OS is activated or not.
>>Go to Start>Run Type oobe/msoobe /a         (add space wherever needed)

>>Press Enter to verify whether your OS is activated or not