Where did you get those monitor stands? What are they called?
It looks like they don't attach to the bottom of the desk, is that right? I've been looking for something similar for my monitors.
They're made by Ergotron, and I cannot recommend them highly enough - they have some of the highest weight limits of any arm out there, and work beautifully. My only complaint is that the arms aren't quite long enough to allow monitors larger than 24" to mount on the double-post mount without using an additional extension.
Unfortunately, they do attach to the bottom of the desk; rather, they're fastened through a small hole drilled into it, held on the other side by a washer and nut.