I got a new copy of Windows XP Pro OEM a few months ago and it was running quite happily and not bothering me to activate it. I eventually let it download updates and afterwards it pops up with the "You have 30 days to activate Windows."
I've reinstalled the Windows copy again (after a virus went beserk) thinking it would go back to the original OEM setting but I get the, "You have 30 days to activate Windows" again. Apparently a quick format of the hard drive wasn't enough, MS has installed something on my hard drive.
I'm not going to activate it because my copy will get locked on the current hardware.
What I'll do is boot up with Linux and get it to format the drive.
The first activation warning was either a flub in Windows Genuine Advantage, or you have a shoddy source for OEM software. The second activation notice, after you reinstalled, is expected since it is a new installation.
You can get the XP installation to do a full format, just select the option without the "Quick Format" bit. It takes longer, but it works. And do not worry too much about activation problems. So long as the hardware ID calculates out the same, you should not run into problems, and if you do it takes a six minute phone call to Microsoft.
I know, it is a lot of hoops through which to jump. Try being a system builder and downgrade Vista or 7, and the horse-shyt we have to go through to do that. I doubt Windows pirates have as much nonesense to deal with.