ASK GABRIELLE Union about the commercial prospects of "Perfect Holiday," a Christmas movie with a largely black cast that opens tomorrow, and she pretty much goes off. She starts slow, with a diplomatic observation that the recent success of "This Christmas" proves that mainstream movies with a black cast will appeal to "all races, nationalities and religions."

And indeed, "This Christmas" put up big numbers against tough holiday competition, opening at $17 million and holding tenaciously to a spot in the top two/three for three weeks.

Union, though, wonders how many times movies with black casts are going to have to prove the point that they are commercially viable.

"It's interesting because I did a movie called 'Bad Boys II' which was all minority cast, all black and Latino. We had one white guy, Joe Pantoliano, and race was never an issue. No one was surprised that it made more than $100 million, and did well overseas," Union said. That big budget action comedy, starring superstar Will Smith and Martin Lawrence, was never considered a "black" film.

"So we start to wonder, if the budget drops to the 10 million dollar range, does it suddenly become a black movie, or a genre movie?"

Her "Perfect Holiday" co-star, Morris Chestnut, echoes her view.

"You look at what Tyler Perry has done ["Why Did I Get Married" opened at $21 million], and for some reason, it's grabbed the attention of the mainstream media. But it's really not new. If you look at the number that Ice Cube put up with the 'Barbershop' movies, for instance, I think they're just as big."

He's correct. Both of the "Barbershop" movies opened at $25 million, and together grossed $140 million. Chestnut said the lesson Hollywood is slowly learning is that moviegoers of every stripe are prepared to accept black actors as part of the mainstream, especially if they're working in a familiar format.

"I made a movie called 'The Best Man' that was pretty successful. It took a genre that was popular at the time, the romantic comedy and the wedding movie, and used black actors, and people wanted to see it," he pointed out.

The $17 million number that "This Christmas" put up on its opening weekend was no fluke. The film remains No. 3 at the box office, holding onto more than 60 percent of its opening audience, an industry benchmark for staying power.

Again, if folks were surprised, director Preston Whitmore wasn't one of them.

"Honestly, I wasn't surprised. I knew that I'd made a good motion picture. I knew that it had the sort of emotional fabric that connects with people, all kinds of people. What connects with people is family - there's going to be somebody in there that you know, or a situation that you recognize," Whitmore said.

Union believes attitudes have changed among the under-30 demographic most coveted by Hollywood.

"I've had little blond white girls come up to me and ask what it's like to kiss LL Cool J ['Deliver Us from Eva'], and I've had African-American women ask me about George Clooney ['ER']," she said.

The irony, Union said, is that Hollywood higher-ups seem to be the last to recognize this phenomenon. They still think a movie can be "too black" - Union said she's lost jobs in recent months when parts written for an African-American were modified to accommodate a white actress.

"I think the people who run the studios don't know the generation they are pandering to. My advice to them is to ask their grandchildren - 'What do you find entertaining?' " Union offered. "Let the box office numbers speak for themselves, and you'll make better decisions." *