PS3 outselling X360 by 2.5m units at the same Timeframe
In 2 years and 3 months SONY sold 22.9m ps3s ww by MARCH 2009

http://www.gamezine.co.uk/news/formats/playstation3/playstation-3-closing-on-23-million-units-$1295495.htm

at the same timeframe(2 years and 3 months) there were 20.3m x360s Worldwide

http://vgsales.wikia.com/wiki/2008_fiscal_year

also the lower end x360 costs 250$ as opposed to 400$ PS3. not to mention that PS3 launched at a price tag of 600$ and was also 500$ for one year.