In continuing helping you guys out, here’s the NCR Quest guide provided by wikicheats.
NCR Embassy
When you get to the Strip, you will come across an NCR soldier who gives you a note telling you to go to the NCR Embassy. The Embassy is also on the strip. Go there and speak to Ambassador Crocker. He will give you the next quest in the chain.
Things That Go Boom
The NCR, like the other New Vegas factions, wants the Boomers on their side. The Volare! quest will make the Boomers pledge their support for you.
King’s Gambit
The NCR is having problems with the Kings, a gang in Freeside.
There are many different ways to complete this quest: If you haven’t yet done the G.I. Blues quest, you can talk to the King and start it. At the end of the quest, you can choose your reward. One of the options is a favor from the King. You can ask him to stop the violence against the NCR, and you will complete the quest.
For the Republic
In this quest, your goal is to ally the Great Khans with the NCR. You do this by completing the quest Oh My Papa.
Mr. House Goes Bust
In this quest you must kill Mr. House. If you have the Platinum Chip or are on good terms with House, you are able to walk right into the his penthouse. When you are standing in front of House, look to the left, under the stairs. There is a terminal you can use. Make sure you really want to get rid of Mr. House, because when you use it, the robots in the room attack. You could try to fight them, but a better idea is to run into the room that opens. Inside you will see an elevator on your left, and next to it a terminal. Use the terminal to unlock the elevator, then use the elevator to go to the control room.
Once here, walk up to the terminal and unseal the chamber. You can then talk to Mr. House, if you like. Return to the terminal and either sterilize the chamber or disconnect house from the system. Either way you will complete the mission.
Brotherhood of Steel
To get the Brotherhood on your side, you must do the Still in the Dark.
You’ll Know it When it Happens
In this quest your goal is to save the president of the NCR from an assassination plot.
Go to the Hoover Dam Visitor Center and talk to Ranger Grant. The two of you will go to the helicopter landing pad. Talk to Grant there and soon after the president will arrive. You will now have to find one (of the two) plots to kill the president.
The easiest way to do the quest is to have Rex with you. Walk near the crowd until Rex starts growling at a man it the crowd. Talk to him, but don’t accuse him of anything. Go back to Grant and tell him the man has explosives.
Eureka!
This is the final battle for the Hoover Dam. You must fight your way into the dam, then confront Legate Lanius.
The mission starts inside the dam. Your first objective is to fight your way through the dam’s power plants. In power plant 3 there is a console, and a valve outside, you can use to turn on the turbines and chop up some of the Legion’s forces.
Fight your way through the rest of the power plants and into the visitor’s center. On the top of the dam, you will have to face large numbers of Legion forces. Keep fighting forward into the Legion’s Fort.
In The Fort you will confront Legate Lanius. He’s a giant of a man, and he is the most powerful single enemy in the game. You now have three options. If you have a speech skill of 100 you can talk him into retreating (just don’t ask him if he’s retreating, because that will cause him to attack). With a barter skill of 100 you can convince him that the Legion doesn’t have the resources to hold the wasteland. If you have neither of these skills, you will have to fight him.
Once you’ve dealt with him, you will complete the main quest of Fallout: New Vegas.
