DKII on 08 June 2007
Parokki - just use the hardware sales comparison charts right on this site.
Wii's first week on the charts is w/e Dec 10th '06. Wii hit 940k w/e Jan 14th '07 and 1M w/e Jan 21st '07, so it hit 950k (what the PS3 is at right now on this site so when it hit about 1M according to PR statements) early in its 6th week, about a month faster than the PS3.
360 hit 950k in mid-April 2006 following an early Dec launch, so it took over 4 months or 17-18 weeks, almost two months slower than PS3.
