You can do this by editing some simple entries on host file.
In XP open C:\WINDOWS\system32\drivers\etc\hosts sample entry is added in it.
If you are using win Vista or later version you may follw the steps to edit the host file
Orginal location : C:\WINDOWS\system32\drivers\etc\hosts
1.Copy the hosts file to another location
2.Edit the entry that need on the file.
3.Replace the file to original location.
That’s it enjoy….!!!!!!!
Activate windows XP
1, Click Start
2, Type regedit
3, Goto the location want’s to editC
HKEY_LOCAL_MACHINE ===> SOFTWARES ===> Microsoft ===> CurrentVersion ===> WPAEvents
4, Edit the follwing events in in the “OOBETimer”
5, Delete the existinv values that in or in other words (Select all and then delete)
6, Type this new value “FF D5 71 D6 8B 6A 8D 6F D5 33 93 FD”
7, You cannot copy and past, so you have to type this in manually, then click OK
8, Then right click on WPAEvents, click on permissions set the System permission Deny fullcontrol
9, Then click OK,
10,Now you open the activation window on XP it says “Windows is already activated”
Its 100% working for me thanks