HALO
Cheaper price
Games
360 is a well known number in america

 WoW, of course he is. He's MikeB. If he isn't collecting a paycheck from Sony he should be. I mean like everywhere else in the world the US has far more PS2 owners than any other competing console. The real reason for the difference is that the Playstation brand was the first home console brand to sell in significant quantities in Europe. Therefore brand loyalty is a much larger factor in Europe than in any other region. When you combine that fact with the 360's cheaper price and better library you get the larger acceptance of the 360 in the US than the PS3. Not to mention the fact that the later launch in Europe allowed the PS3 to have a much better launch lineup than the PS3 had in the US.

Better games, more games, same graphics and cheaper price than PS3.

 A better question is why PS3 is more popular in Japan/Europe. Possibly name recognition?

Sony and Microsoft are both corporations and we all know how trusting such entities can be.  But, come on, I thought that Sony advertising Assassins Creed and Call of Duty 4 as Playstation only games was pretty low.

A vastly superior lineup of Western and PC-Centric gaming.

The US was dominated for years by PC gaming - even back to the old C64 days. Many PC gamers never went for the NES, SNES, and such until MS "bridged the gap" and put more PC-Centric gaming fare onto consoles. Namely Halo, which was supposed to be a PC-Only title until MS bought Bungie out to throw Halo onto the Xbox.

So you basically have:

Xbox 360:
Strongly West-Centric Content
Strong PC-style content
Large Online gaming community supported since 2002 on the Xbox)
Focus on Hardcore and Core gaming
$279.99 Price Point

PS3:
Weaker West-Centric Content (but stronger J-Content)
Less PC-Style content
Mediocre Gaming community (established in late 2006 w/ launch of PSN, very little PS2 support)
No focus on hardcore/core gaming
$399.99 price point


Which one interests the average American gamer more? The system with the more games that they like? The answer in any country is yes. Europeans go for the PS3 because of PES and Fifa, Americans go for the X360 because of Halo, and the Japanese go for the DS for training games.

Halo

I've seen WAAAY more multi-platform games showing only the 360 logo in advertisements, so don't call Sony low for doing it in 2 games

 actually your wrong on that. The PS3 supports Linux and a USB mouse and Keyboard so its the otherway around. 

 QFT

 *cough*Disc Read Error *Cough* Excuse me what I meant to say is Sony for the past 2 generations has had its share of problems like not being able to read discs for example, while Sony did nothing to really address this problem, at least Microsoft did, fixed it for free, and extended the warranty 3 years.  Xbox Live has its issues like any other internet service it happens, but it gets fixed ASAP, and it's not constraining to your online experience like PSN.  One thing you got right is we love where we live.