Former WB watchers, mark your calendars. It's time to say goodbye. Those of us who can remember a day when the WB was the place to catch vampire slayers, randy teens, and preoccupied college girls with amazing hair will undoubtedly want to tune in to the WB on September 17th for the netlet's send-off. Variety is reporting that, before the WB and UPN morph into a single entity, the WB is taking a trip down memory lane and airing the original episodes of the network's long-gone critical darlings Buffy the Vampire Slayer (the two-hour pilot), Dawson's Creek , Felicity , and Angel in a single block. The event will occur on Sunday, September 17th, the night before the offical launch of the CW, from 5 pm to 10 pm. The WB's sign-off schedule, which will include classic promos from the netlet's 11 year history, is as follows: 5 pm: Felicity ("Pilot") 6 pm: Angel ("City of...") 7 pm: Buffy the Vampire Slayer ("Welcome to the Hellmouth"/...