NCR. Cool guns and armor. But I normally just grabbed a silenced sniper with AP rounds, high sneak and 100 guns, then put hidden critical headshots into every ranger in the game. Now I'm rolling in Gov't rounds, ranger sequoias, brush guns, AM rifles, and all of their gear.

Brush guns are awesome, they last you up through level 25. I'm trying to work for the NCR now, but my first mission is the Boomers quest, which I've done near 40 times, all of them killing everyone in Nellis. Can you do that with the NCR, or do you actually have to make them like you?

You can make them like you. When you first get to nellis through the front gate, the guards will take you to Mother Pearl. She will give you some quests, as will Loyal. Doing those quests will increase your rep with them, but you can also listen to the history of the boomers at the museum. Also, if you have the rockets and/or dinosaurs that you get in novac, you can give those to the children to increase your rep. There's one last one, which I don't reccomend as it uses valuable missiles (which you can sell at gun runners for high caps), where you give missiles you have to raquel to up your rep.