Pink Floyd rocker Roger Waters will tie the knot with longtime fiancée Laurie Durning. The Floyd founder, for whom this will be a fourth marriage, and the pretty blonde, a filmmaker, will wed before Waters hits the road early next year for his tour. After a seven-year engagement, Durning told us over lunch at Amaranth the other day, “It just seems like a good time to do it before the tour.” The couple is shopping for a new engagement ring to replace one Durning lost in London after Waters popped the question. But don’t expect a Paul McCartney-style extravaganza: Durning says she’ll only have close friends at a “private and low-key” ceremony.