There is also Nuclear Renaissance 2 by Ramshackle. Not quite Fallout in setting but a good fun ruleset.
There is also a Fallout set of rules for THWG Chain Reaction. It works well.
Some gamers use the Necromunda rules for Post Apoc. The power armour, energy weapons and Ogryn stats already exist in the 40k rules so it covers it pretty well.
Being a mainly Post Apoc gamer I have tried most of the rule sets mentioned. MDRG is good fun but misses the Super Mutant and Ghoul stats of Fallout where they are stronger. I love the Skank rules but many don't like the mechanics. Wastelands 3 Meltdown is great fun and has a superb campaign system. Chain Reaction 3 plays well and is great for solo play.
I find