you dont really have to have a date, just have a column that stores the week number you want the record to be shown for.
for example, running the following query:
SELECT DATE_FORMAT(CURDATE(),'%v') as weekNum
returns 20 for the current date 5/19/2010. This is the 20th week in the year.
So any records that should show this week, should have the week column set to 20
For the sake of example, lets say we add a column to your table for the week number and name it "weekNum".
To get the records for this week we would use:
SELECT * FROM tblName
WHERE weekNum = DATE_FORMAT(CURDATE(),'%v')
assuming that the value stored in weekNum is 20, those records will be returned.
the '%v' format return 1 - 53 where Monday is the fist day of the week. If you want Sunday to be the first day of the week, use '%V' instead