have you updated to IE8?
are the date and time correctly set?
http://www.wikihow.com/Activate-Windows-XP-Without-a-Genuine-Product-Key
you can try the steps above but I have not used this method , my system activates fine with every reinstall so far,

because I follow the following steps:
Create the Activation Status
Navigate to system32 folder.
Copy the wpa.dbl and wpa.bak files
Reinstall XP in the normal manner
Restart the computer and use the F8 key to bring up the Advanced Boot Options
Select Minimal Safe Mode using Up and Down Arrow Keys and press Enter.
Navigate to system32 folder.
Rename the existing wpa.dbl and wpa.bak files.
Copy the previously backed up wpa.dbl and wpa.bak files to the system32 folder.
Reboot the computer.
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https://support.microsoft.com/en-us/kb/312295
do not use the guided method, it has not been available for years
and if you try phone, DO NOT push any buttons, just wait until you will finally get a human.
