When you load Op. Anchorage up, you find a broadcast signal from some of the Brotherhood Outcasts requesting help. When you travel to their location you find some Outcasts fighting it out with Super Mutants. After those guys are taken care of, you talk with the Outcasts and they tell you about the Anchorage War Simulation that is protecting some advanced technology, but they need your Pip-Boy to access the simulation (Behind a locked door there is a dead body with their arm cut off; they tried to cut off the Pip-Boy from the guy's arm and it didn't go too well). The simulation is entirely just a shooter. There are lots of guns and every so often there are health and ammo dispensers as you have no other way of healing. As far as the missions go, they're your basic kill everyone on your way to point X. It's not quite what it should be, but it's not terrible. They could have done a better job with the story of the Chinese invasion of Anchorage though, and it would have been more interesting. The real reason to buy Op. Anchorage, though, is the gear that the simulation is protecting. There are some incredibly awesome pieces in there and for me it was enough to justify the cost to me, but if you're not apt to pay $10 for some guns and armor, then you can safely ignore Operation Anchorage.
The Pitt
The Pitt is the ruins of Pittsburgh, Pennsylvania. About 30 years before the game, the Brotherhood of Steel went through The Pitt, killing all of the mutated horrors they found. Now though it's turned into a slavery operation to mill steel again. The radiation is so bad that the people who were left in The Pitt soon mutated as well, into Trogs. When you load The Pitt, you get a radio signal of a man who need your help, claiming that there's a cure for the mutations but the slavers are holding it back. If you decide to help, you have to give up all your gear to become a slave and infiltrate the milling operation in order to find the cure. The Pitt is a pretty depressing wasteland, even more gloomy than the D.C. area. Trogs are initially rather quite dangerous as you really don't have much in the way of weaponry or armor, so you'll initially have some intense fights and tough decisions about health and your radiation levels. The story of The Pitt is pretty good, definitely worth checking out, with plenty of opportunity for good and evil. As with Op. Anchorage, there is some pretty sweet gear to be had (especially in combination with the gear from Anchorage) making The Pitt a great addition to Fallout 3.
Broken Steel
If you only buy one DLC pack for Fallout 3, it should be Broken Steel. It is easily the best one of the three. After the ending of Fallout 3, normally the game is over and that's it. Broken Steel adds in new gear, new, tougher enemies, a new quest about the same length as the other two packs, and raises the level cap to 30 along with some new perks. The raised level cap in particular is pretty sweet. At level 20, you're pretty awesome in the game, but at level 30 you'll be pretty insanely powerful. My lowest skill was at 70% and several skills were maxed out. The new enemies and gear are also pretty awesome. The new Enclave Hellfire Trooper has a really cool fire artillery weapon and neat armor. Albino Radscorpions and Feral Ghoul Reapers are tougher and more deadly than their normal counterparts, and the new Super Mutant Overlord is more plentiful and just as dangerous as the Behemoths with their Tri-Beam Laser Rifles. The new perks are hit or miss, I found myself only taking a few of the new ones as mostly they weren't that interesting, but there are a couple that are actually useful. I can't say much about the plot of Broken Steel without spoilers, so I'll just say that it continues from the end of the regular game. Broken Steel is definitely the best DLC pack and worth picking up unless you have an aversion to paying more money for DLC.
I have no idea. I get occasional hard crashes, but nothing that bad. I should say it's been a hell of a lot worse since moving to Fista than it was on XP.
