My PC:
- AMD Phenom II X6 1055T
- ASUS Crosshair IV Formula
- G-Skill 16GB DDR3
- ATI Radeon HD 5450 (1GB)

F:NV runs horrifically slow and choppy, especially when turning camera or moving, regardless of settings. (It also has a mouse sensitivity problem but I fixed that.) I see Youtubes everywhere of my video card running F:NV on ultra high and max resolution seamlessly, though. I updated all my drivers, too. My computer should be able to run this, and just about everything else, at freaking once.

Strangely, F:NV runs coooompletely seamlessly on my less-impressive laptop on top settings/resolution.

In summary: WTF, and how do I fix this?

You have a snail-slow video graphics card, only intended for basic business, and simple web surfing, not for game playing. The minimum graphics is an X1650 XT, which was a medium card six years ago, but is very slow today, like an HD 5450. The HD 5450 cannot run with that elderly card, however:

http://www.gpureview.com/show_cards.php?card1=625&card2=472

You need a video upgrade badly, if you have a good enough power supply to support the improvement.