And that's not a very good article either. This does nothing to get around the fact that you'll still be running an EOL OS with no security patches.
The risk is that as holes are found in Vista/7/8, it's feasible they exist in XP too. Hackers know that XP won't be fixed, so as they see MS patching the holes for the other OSes, they'll attempt to use the same vulnerabilities against XP. Saves them from having to find them. If they get in, great, if not, at least they didn't spend countless hours trying to find the holes.
If you really must run XP still (and I'm not sure why), then it should be entirely disconnected from the network if you want it to be secure.
That being said, most corporations that are still stuck on XP have purchased extended support contracts from MS so they'll continue to get critical patches. I surely wouldn't be surprised if these get leaked out onto the Internet for the public to download as well.