It makes perfect sense the way it's worded right now(the choices, not the output) as long as one bothers reading. First choose the starting week ending on a certain day, which is 7 days of sales automatically. Then choose the the final week which ends on a certain day.
Perhaps the output should be changed to be more clear from
"VGChartz Hardware data for the period 31st Dec 2006 to 31st Dec 2006:"
to
"VGChartz Hardware data for the weeks ending 31st Dec 2006 to 31st Dec 2006:"
Another option if it's possible is to change the choices for the starting week to the first date of the week. Then the output would be as follows:
"VGChartz Hardware data for the period 25th Dec 2006 to 31st Dec 2006:"