I still can't fathom why you don't let the DB do the work for you in this scenario. 
If all you're after is the number of records within a given date range from today (or any arbitary date), going backwards...
Code:
<?php
// subsitute these vars for whatever you need
$table = "whatever";
$date_col = "date_created";
$interval = "WEEK"; // or MONTH or YEAR etc
$int_count = 1;
$cur_date = '08-05-09';
$query = "SELECT * FROM $table WHERE $date_col <= $cur_date AND $date_col >= DATE_SUB($cur_date, INTERVAL $int_count $interval) ORDER BY $date_col DESC;"
$result = mysql_query($query) or die(mysql_error());
// you now have a MySQL result resource containing all records from $table within the last week, ordered by the date column (newest first).
?>
Obviously sanitize variables to prevent injection etc if they are user editable.