DESPERATE HOUSEWIVES - "Desperate Housewives" concludes the season in fitting fashion with a dramatic two-hour Season Finale, SUNDAY, MAY 18 (9:00-11:00 p.m, ET) on the ABC Television Network. In the second hour, "Free" (10:00-11:00 p.m.), several residents of Wisteria Lane are faced with deadly threats, and Katherine Mayfair's secrets are finally revealed. (ABC/CRAIG SJODIN) DANA DELANY, MARCIA CROSS