its not microsofts goal to outsell sony, its to make money
But by selling less they will ultimately make less money ;)
The reason I say this is that it's all about PSN/Live imho. The more people that move over to Sony, the more pay for PSN, the less people pay for live, which ultimately affects MS's bottom line. Sony were very smart in doing a paid PSN because it means they make more revenue, but every single customer they get which moves over to them could have an impact on the profit that MS makes (and they were making alot from this).