did u put the arrival of Halo: ODST in consideration? That's at least another 20-50,000 more for the 360...
And I find that kinda low considering that barely any exclusive came out for the 360 Sept of last year and it still made 347,000 that month. and yes this is NPD numbers we're talking about.
Worldwide was 862,000 (X360) vs 670,000(PS3)...