I don't get it. Can I work for House without pissing off the NCR? I want to do as much quests for every faction as possible without having to choose a side - making quests for the other factions impossible to do. Do I have to start a new game for every faction I want to help?

I was actually wondering this myself. I was about to make a thread asking if you can basically play every angle until the very end, considering they everyone, including Yes Man, has extremely similar quests, and then just screw everyone over by finally picking one of the four at the last second.

You have to piss off them at some point, the wiki suggests that the choosing point is to who you report the Boomers. Except Yes Man, he's always available.

You can only complete the game for a single faction although you don't need to make a decision terribly early on. In fact near the end of Mr. House's quest line there is one mission you'll only get if you still have a positive reputation with the NCR.

For instance the quest "The House Always Wins". It leads directly to the final quest "All or Nothing". So this will mean that I won't be able to complete "The House Always Wins" if I decide to start working for House and then change my mind and work for the NCR until the end.

This is seriously pissing me off. It's either / or for me. Not starting quests and not being able to complete the task.

It's called replayability.

Just save your guy at the gates of The Strip, Level 30, then you can do any ending you wish...

Um, no.
Well I mean you can if you want...
I have found it to be more of a process of elimination.
First Caesar will vilify you (unless you are working for him) - and then there are 3.
Then actually Mr.House is the next to go (unless you are working for him).
You can remain undecided between NCR and YesMan until very near the ending.
I saved the President for the NCR, and was right to the end - but I was still able to choose to bail and switch to YesMan.
So it's easy to do both those endings; Mr.House requires a bit more of an early commitment; and Caesar? It's obviously all or nothing, with him and his Legion.
Hope this helps,
Regards

You can stay friendly with all major factions, however that requires some study of Fame/Infame gain.

I was favored by all factions except for Caesar's Legion when I went to the fort to retrieve the platinum chip. I was neutral with Caesar's Legion. I saved my game at that point. I was able to use that save to complete all the quest lines. I had to commence from that point four different times to complete them all.

Hmmm, did I do the wrong thing by telling every faction that the Boomers are on my side and will do what I say? :unsure: Should I have only told one faction?
I'm at the point where the Legion and NCR both are not happy with my choice to continuosly help Mr House and my quest page warns me that each faction will turn against me if I continue to help him.
I've tried killing and disabling him but always felt terrible afterwards, so each time reloaded and helped him instead.

I do have a second character up to around the same point in the main quest so I guess if I screw something up with one character I'll know what not to do when I play the other one :shrug: