<?php
  $date_time = "11-02-2010 18:50:00";
  
  $date = strptime($date_time, "%m-%d-%Y %T");
  $ut = mktime($date['tm_hour'], $date['tm_min'],   $date['tm_sec'], 1+ $date['tm_mon'],   $date['tm_mday'], 1900 + $date['tm_year']);

  $now = time();
  if($ut >= $now && $ut <= ($now + 7200)) {
    echo "ok";
  }

ok