Yes Live is a big portion of the money they make. Your numbers aren't quite right though. First off not every 360 owner has gold live (I don't for instance since I seldom turn the console on and have a PS3/PC), the last numbers I saw had it at around 10 million. But not all 10 million pay 50 a year, some pay monthly at a higher rate (I think its around 7 or 8 dollars) which comes out to almost 100 dollars a year. Lets say on average they pay 60. So thats 10,000,000 people at 60 dollars each, that gives you 600,000,000 which is a lot. Then toss in the microtransactions they hit you with (there is almost no free content on the 360, unlike the PS3 where themes and all the rest are usually free). On average lets say each Live user (all 25 million this time, since you don't need gold to use live content transactions) spends around 50 a year between games, movies, themes and the rest. That is then 1,250.000.000. So yes they are nickel and dimeing all the 360 owners for around 2 billion per years but not in the way you were mentioning (its more the content then live where they get you).
On top of that of course you can't use 3rd party Hard drives so you have to pay almost 200 dollars for a 120GB drive; you need to buy wireless even on the elite for a 1st part 90 dollars ect ect. Microsoft might make the console cheap, but they get hundreds of dollars out afterwards for all the things that are free with the PS3.
In reality, an 80GB PS3 for 399 costs less then a 199 core+200 for 4 years of live+90 for wireless+100 or more for a hard drive but a lot of people are taken in by something that seems cheap and don't really notice the recurring costs. Microsoft thrives off of that; I guarantee you there are people on this forum who have given Microsoft nearly 400 dollars by now for online play between the Xbox and the 360, paying more then the console is worth to do what I've been able to do for years free on my Playstations.
PSN ID: ChosenOne feel free to add me
