About VGC data, I'll calculated the "resonable range" it suggest, following those points: Some of VGC sources report also the Sunday, so they have a half sunday more than NPD will have. Calculation out canada, and 5% VGC wants to be above NPD (site owner said yesterday) and an error of 20% this is what I came up with:
2
360: 497k - 746k
Wii: 165k - 248k
PS2: 157k - 235k
PS3: 72k - 108k
Of course thats a rough calculation and VGC could be more of NPD than 20%, so take these how you will.