Which one of these cameras is better for professional looking headshots?

I'm thinking about buying a DSLR, but I was wondering, which one of these cameras is good for taking really good professional looking headshots?

Canon 7D vs Nikon D7000

Also, can you tell me if both cameras are really good and also why the one you choose is better?

The right lens would make the difference

Just looking at the brand names, I would go for Nikon because I find Nikon cameras have strong built bodies, and very good quality photographs especially up close like Macro or your preferred HeadShots.
Every Canon camera I have tried had a wobbling sound when shook, or it had loose pieces.
If I where you I would choose the Canon EOS 7D DSLR. Because it is one of the best cameras I have seen for it's price
Range.

Lens and lights are the key to great portraiture, camera make and model mean squat

any old camera can be used they are just recording devices, compare them at dpreview.com if you like

Holy G! Comparing a Nikon to a Canon DSLR is pointless. In the hands of someone willing to learn the basics of photography either one will produce excellent photos. To second part of DCMB's answer, lighting is everything. Learn to use it and that includes ambient.

It's not the camera, it's the artist tat produces good headshots. I've known people who have spent thousands of dollars on equipment and the most up-to-date camera and lenses that consistently turn out crappy work because they don't have the talent and work everything in auto, and just aren't willing to learn. Inversely, I've known amazing photographers that can get professional-looking photos with a point-and-shoot or even an iPhone.