There are cracks and keygens for everything...

Here's the easiest trick: get a job and actually buy the OS.

Actually thats much harder to do than downloading and running a simple crack :P

I have a copied version of Windows XP here. I'm still on SP1. When I go on windows update V5, I see that a file is trying to access Internet(c:windowssystem32oobemsoobe.exe aka "Microsoft Out of Box Experience") . I blocked this file's access and I can use V5 without problem. It will take a little longer to scan for the updates, but I don't have the "Invalid Product ID" message.

What the hell are you on ? your computer will be gone in 30 days lol. I have a legit copy of winxp pro and after slipstreaming SP1 my legit key no longer worked. I now use a keygen to make my original copy of XP work. I figured a keygen was a lot easier than not installing sp1. so yes they might block some keys and legit ones also , but now I have sp2 on and update works fine . my original key still dosent want to work but I can live with that. Typical Microsoft crap.

Just use the simple solution, BUY the operating system if you're wanting to use it. What do you do if you want a Radeon X800? A. Buy it or B. Go into BestBuy & shoplift it? If you're wanting to use it, just buy it, or else you deserve everything you get.

I concur, because of the endless activation garbage my paid-for xp cd sits comfortably in its box while the "corp" version gets used without even the slightest hint of trouble.