I'd recommend aftermarket filters if you're REALLY going to use them. Average gamer though, not as much. You have to open up your case and clean it out about once a year anyhow, so filters aren't THAT crucial. HardOCP is probably an overclocking website, am I correct? Those guys are enthusiasts, and they fall into a different bracket alltogether.
I'd use the filters that came with it. My Antec DF-30 has built in filters that seemed BS, but after about three months of use since the last clean, I can tell you that they WORK. Don't be afraid to use the stock filters, aftermarket filters may very well hamper airflow and increase noise levels.
I'm going to revive this thread, since I have a HAF X myself.
"Dustfilters" where included everywhere, but the only things I have are metal mesh honeycone things in front of every intake fan, which let in the dust without any problem.
Are these the actual dustfilters or did my case come without any?