In the United States, for the week of May 6, Wii outsold Xbox 360 by 32,000 units. If this rate were to continue unchanged, Wii would catchup to Xbox 360 in mid-may 2009. However, there are two reasons why Wii will not catch up to 360 in the United States - price drops and the 360 2007 software lineup - both of which will offset Wii gains until it is too late to catch up.
Below you will find numbers to justify these claims. Numbers in thousands are the 'extra' units Wii sells each week beyond what Xbox 360 sells - the rate of gain. The multiplied number is the time (in weeks) that rate of gain will last.