Black Mesa Source

xbox live has just as many subscribers, so that point is void.

as for advertising, Fallout 3 was advertised on xbox, ps3, AND pc.
xbox sold 55% of the copies alone, ps3 has 28%, and PC had 17%…

http://www.product-reviews.net/2008/11/17/fallout-3-sells-most-in-series-xbox-360-has-55-of-sales/