Yeah, all I did was stick in the cd set, and it ghosted the files onto the HDD, and XP started right up with no problem. It took me to the start screen where it says "welcome to MS windows". The original board in that system was an Intel D845GVSR, which had an AMI BIOS on it. The board I stuck into the emachine was an Asus P4B533-VM, not an OEM board, it has OC'ing features and is supported by the Asus website, which it has an Award Medaliion BIOS on it. I was able to complete the start menu, go into windows and Activate it just fine. I think the people at Emachines like to make up a lot of stuff to get you to buy their motherboard for $150!! 150 dollars for an old outdated board that is probably only worth $35, since it's in intel board.

Yeah, I was really shocked that it worked though. I guess it was because the Intel board and Asus board had the same chipset, LAN, sound, IDE controllers and some other similar things.

That is pure Bull. We repair eMachines every day. We use new, pristine hard drives. We use the eMachines install discs. There is never a problem.
However, those who say you can use the product ID off an eMachines certificate of authenticity with a Windows XP OEM disk are full of it, as well. That was only true of four eMachines, and they had it long corrected by the time yours came out.
The real problem is that you have one of the high failure motherboards. I doubt you will get it working properly until you replace the eMachines board with another eMachines board.
So now is the perfect time to upgrade to a better unit. Any money you spend on that unit will be money flushed away.

I have used OEM XP discs to fix OEM computers from customers who needed a XP repair or a true clean install of the XP OS without the preinstalled junk. Using the key on an emachine with an OEM XP CD has worked fine for me. It activated just fine as well.