Hello, I am very familliar with your problem. I have an original windows xp home edition cd, i formatted my computer alot of times because of spywares and problems and such.
There is a limit of times that you can reactivate your windows over the internet. After formatting your computer or reinstalling the windows again.
But that number is not 5. It's more than that. I reactivated my windows on the same computer about 10 times. and after about 10 times, it told me this : The number of the times that you can activate windows had been exceeded. Please use a different activation code.
It isn't forever even on the same computer, but if you still have your cd key that you activated the windows with. All you have to do is call the microsoft's windows activation phone number. They have a special toll free number just for that purpose.
There's both a toll number, and a toll free number that you can call according to your country. The Phone Number is included in your Windows xp home edition CD.
I called the number and told the representive with my cd key that i used before, and i typed in the numbers that he gave me on he phone, and it was activated instantly. it's very easy.
Although it says once you bought the cd and cd key, you can use those forever to activate windows on the Microsoft site. You can't via internet. So you'll have to call the representitive and they will most likely give you a new code to enter ( But this code is for one activation only and is not the same code as the code you bought, it's a different kind I think ).
If you would like more help and or have questions. Please private message me and i can help you if you couldn't activate your windows.
Thank you, I Hope I've helped. Bye.