Enough was enough. One more movie about a dragon, a man of steel, a minimally intelligent son of a Titan, a doggie, even an Ark with supernatural umph and it was back to Mahler and the Mandrell Sisters.

Then out of the magical movie mists came "Arthur." And, praise the Valkyries, the hero is not the ill-begotten son of Uther, king of England and lord of Camelot. No, he is a man with no mystical bent. No urge to slay dragons. No Titans to slash. No foxes to flay.

Arthur Bach is just plain folks, an alcoholic with a sense of humor, an electric train set, a chauffeur named Bitterman and $750 million. He loves wealth and power, enjoys his addiction and unashamedly turns on his toy choochoos while making love, which incidentally is a private affair. Sex and violence fans will be minimally gratified by this film.

(Face it. Dudley Moore is cute as an oldish button, but he's no Burt Reynolds. Even if Bo Derek shows her scalp and plays. "Bolero," Dudley doesn't do it like a macho man. And when Liza Minnelli is standing in for Bo, odds are 10 to 1 his romantic potential is going to be comedically castrated. Two kisses. That's it.)

Minnelli, who's looking a little frumpy this film, wasn't up for much passion, either. She's all liquid-eyed and poignant as Linda Marolla, waitress with heart of gold. Linda and Arthur meet at Bergdorf's, where she's shoplifting for her father's birthday and he's buying a gross of sweaters, all green.

John Gielgud, fabulously funny as Arthur's valet and surrogate father, Hobson, acknowledges the encounter: "One usually has to go to a bowling alley to meet someone of your caliber." Minnelli is brash, humble, indigent, as she boards the bus for her horrible tenement in some ghastly borough of New York.

There's a minimum of Minnelli this film, but what there is is swell. Not since the prince met the pauper, not since Janet Gaynor got her preppie in "Keep Your Sunny Side Up," has a poor girl more deserved to get her magnate.

In most Cinderella movies, rich guys are brats, snobs or playboys who would benefit from a little old-fashioned common sense, which the poor are capable of dispensing by the bucketful. And most of the time, the young moguls are already engaged to one of their own, usually a silly twit, a giver of wild cocktail parties or a haughty nabob named Pidge.

In Arthur's case, the lady, portrayed by Jill Eikenberry, is a twit, albeit a pretty one. And should he refuse to wed her, his grandmother, an unappealing old bluenose with a penchant for prurience, will deny him his inheritance: "Make no mistake, Arthur," she threatens, "You're too old to be poor."

And grandmother Bach is too aristocratic to be quite so horny. As interpreted by Geraldine Fitzgerald, Gran's a weak imitation of Ruth Gordon, forever pestering her grandson about promiscuity. Old people as sex kittens. Better than Brooke Shields maybe, but still not so funny.

Not to worry. This film's got funny to spare. Gielgud is masterfully comedic, surpassing his role as a British Tonto and galloping away with a Hi-o, Socut. Moore is adoring acolyte, sharing a stolen scene with warm wit.

In their first scene, Hobson wakes Arthur and the prostitute with whom he has spent the night. He shoos her away and offers Arthur coffee.

"I'm going to take a bath," announces Arthur.

"I'll alert the media," sneers Hobson.

"Would you like to run the water?"

"It's what we live for," says the valet.

This is a film to live for, a respite from gore and tension. It's a gentle film, fastpaced with time out to touch you. Best of all, it's about people, warm-blooded types not about to buckle on a sword to solve their problems. Billionaires have their troubles too, you know.

Arthur--At the AMC Carrollton, K-B Baronet West, K-B Georgetown Square, NTI State, Old Town, Showcase Mercado, Showcase Vienna, Springfield Mall and West End Circle.