I found a great article that helps you activates your Windows XP Without product key.
Here are the steps,
- Click on Start
- Find and Click "Run"
- Type: Regedit
- Click the plus next to "HKEY_LOCAL_MACHINE"
- Click the plus next to "SOFTWARE"
- Click the plus next to "Microsoft"
- Click the plus next to "Windows NT"
- Click the plus next to "CurrentVersion"
- Click "WPAEvents"
- On the right panel, find "OOBETimer" then double click it.
- Now, Delete all the Values by highlighting it, then delete it
- Then type in this value without the quotation mark "FF D5 71 D6 8B 6A 8D 6F D5 33 93 FD"
- Then after that click OK,
- Then on the left panel right click WPAEvents, then click on permissions
- Then click System or SYSTEM, then Deny Full Control, then Click OK.
- Then Exit Registry Editor by Click the X or the red X on the Upper Right of the Title Bar or press ALT and F4 at the same time.
- To Verify that it works, go to start, then "activate windows", or go to start, then all programs, then "activate windows"
- If it says that Windows has been activated, then the trick works, if not repeat these steps or watch the video instead (see below)
Hope it will be useful.