I could see a Fallout TV series being good IF:
1. The creators love Fallout and know all about it. Who would be a good? I can think from the top of my head about Joss Whedon (for that "western sci-fi" taste of Firefly) and Jericho's writers...
2. The series STAYS THE FUCK AWAY from the games' plot and focuses on other stories and plots in the universe, at least directly. But say, the main character travelling to The Hub and during his stay, he ends barters some of his stuff with a certain fellow that wears armor with parts of strange blue clothing visible and has a long-haired dude with a SMG, a gas-mask wearing, shotgun-toting fellow with a Nevada accent and a gray-black dog as his loyal companions. Something like that would be great.
3. Keeping to canon should be important. Super-intelligent AIs the size of a house are ok. Microchips and Transistors are not, unless they are somekind of super-top-secret governament technology that makes a small cadre of scientists drool because they managed to cram more processing power within that enormous house-sized AI. Lasers and Plasma Weapons are ok (but should be as rare as guns were rare in Mad Max, no silly "Every other wastelander has a futuristic lightbringer on his holster" nonsense), but a flying car is out of question. (ok, maybe one PROTOTYPE flying car that is dangerous, inefficient and never went to assembly line)