Preview RECOMMENDED VIEWING THIS WEEKEND by Gerard Gilbert

Rock Family Trees, 9.00pm Saturday BBC2 The Saturday Night Armistice, 9.50pm Saturday BBC2 The New Jerusalem, 8.00pm Sunday BBC2 South Bank Show, 11.00pm Sunday ITV

The big picture

Once Upon a Time in the West

Sunday 10pm BBC2

It may be futile to speculate on the best western ever - but it's always enjoyable. Once Upon a Time in the West has got to be a contender. From the very opening sequence - a tense shoot-out at a remote railroad station in which a fly plays a prominent role - Sergio Leone's direction rivets the eyes and the mind. Eyes blazing for all they're worth, Henry Fonda is strikingly cast against type as the ruthless contract killer in black, and Charles Bronson makes for a suitably driven opponent. The proceedings are accompanied by one of the most evocative scores of any film - take a bow, Ennio Morricone. A cordon bleu spaghetti western.

The big match

South Africa v New Zealand

Saturday 1.10pm ITV

The only rival to Imran Khan and Jemima Goldsmith in the column- inches count this week has been All Black winger, Jonah Lomu. Several tons of newsprint have been expended in trying to work out "How To Stop Jonah the Whale". The best suggestion was to get Christo to wrap him up and turn him into a work of art. ITV's coverage of the Rugby World Cup - which reaches its climax today with the final, between South Africa and New Zealand at Ellis Park, Johannesburg - has had its critics. One newspaper cruelly referred to presenter Mary Nightingale as a "Barbie Doll", but there's no arguing with the ratings. Last weekend's semi-final between England and the All Blacks netted 9.5m viewers, ITV's highest Sunday afternoon figure for years.

How did a Sixties blues band called Fleetwood Mac evolve into the introverted acoustic dreamers responsible for "Albatross", before reincarnating into the West Coast giants whose small blonde Nashville- voiced singer, Stevie Nicks, beseeched us to not stop thinking about tomorrow? "Yesterday's gone... yesterday's gone", but not as far as rock historian Pete Frame is concerned. His much-loved (and not just by air-guitarists in anoraks) Rock Family Trees (BBC2) has now been fleshed out into a TV series - and a thoroughly enjoyable one at that.

It's a touch bewildering at first, as the names of Fleetwood Mac's antecedents come thick and fast like some pop version of The Old Testament's Sons of Gideon - The Cheynes begat Shotgun Express who begat John Mayall's Bluesbreakers, and so forth. But, like the Old Testament, the plot thickens and the main cast emerges from these promiscuous comings and goings.

There was haunted, haunting guitar genius Peter Green, for whom the name "Munich" didn't mean an air crash but the night his drink was spiked with LSD. After the bad trip he started wanting to donate the group's profits to charity.

Fleetwood Mac also suffered from walking guitarists - one to the Children of God (where he remains today), while their first American left muttering that he thought the original Mac members were too stuffy and British - "like they were on appointment to Her Majesty". Their final guitarist, Lindsey Buckingham, started strangling Stevie Nicks, until Nicks told him that if her brother and father didn't track him down and exact revenge, the other band members would. "Go now!" said John McVie, and Buckingham left the band. "I meant go out of the room," says McVie, 10 years too late.

An altogether more tragic chain of events is the one that led from William Beveridge, Nye Bevin and the well built, green-site New Towns that were supposed to house citizens of the newborn Welfare State, and the dream's nemesis in system-built blocks forced on people by autocratic councils and the builders who lived in their pockets. The distance from Clem Atlee and Harlow New Town, to T Dan Smith and Rownan Point was just 20 years, and The New Jerusalem (BBC2) charts events with clarity and heaps of unfamiliar archive footage. Future films will look at the Welfare State's response to education, health and poverty.

The new comedy show from Armando Iannucci, eminence grise behind The Day Today and Knowing Me, Knowing You... with Alan Partridge is called The Saturday Night Armistice (BBC2). I think I prefer the title that appeared on the preview cassette, which was "scenes from an out-of-date pilot". The real thing is being filmed nearer to transmission, but the scenes from the out-of-date pilot were highly promising.

"From faked orgasms to cheating husbands - an essay on cannibalising a life," says Melvyn Bragg, by way of introducing Rebecca Frayn's South Bank Show (ITV) film on Nora Ephron, the screenwriter of Heartburn, When Harry Met Sally and Sleepless in Seattle. If Ephron does cannibalise her life, she learnt on her mother's knee. Screenwriter Phoebe Ephron told her daughter "everything is copy" and Nora had the unsettling experience of watching James Stewart, in the film Take Her, She's Mine, read direct quotations from her letters home from college. Lying on her death-bed, Nora's mother hissed: "You're a reporter, Nora. Take notes."