Roseanne and Tom alert! Roseanne and Tom alert!

If you're anxious to avoid more exposure to television's most overexposed (and nauseating) couple, stay away from tonight's installment of "A Current Affair" (10:35 p.m., Ch. 13). Believe it or not, Mr. and Mrs. Arnold are hosting the Fox tabloid show.If you're a glutton (pun intended) for punishment, you'll get to see such exciting highlights as home videos of Rosie and Tommy. (Gag!)

How interesting that Barr and Arnold have gone from suing tabloids to hosting one . . .

LAWYERS LEAVING: The firm of McKenzie, Brackman, Chaney, Kuzak & Becker will lose at least two lawyers - one of those behind the scenes - and may lose a couple of others next season.

Susan Dey (Grace Van Owen) has made no secret of her desire to leave the series. And neither Harry Hamlin nor Jimmy Smits has signed new contracts.

But the greatest loss to the series may be the one viewers will be least aware of, at least initially. Executive producer David Kelley, a lawyer himself, is leaving to produce a new series for CBS.

Kelly, who's been with "L.A. Law" since it began, has been a co-writer of 60 percent of the series' episodes (and all but two last season). He's been e.p. since co-creator Steven Bochco left two years ago.

Kelly will, however, remain as a consultant, as has Bochco. And with the demise of "Cop Rock," Bochco will apparently become more involved in the series than he has been the past couple of years.

Meanwhile, on the acting end of the business, talks are continuing with Hamlin (not that he'd be greatly missed if he left) and Smits may make "cameo appearances" next season.

All of the other actors have signed to do a sixth season of "L.A. Law."

PEACOCK HEADACHES: We talked last week about how Paramount is demanding an exorbitant amount of money from NBC to produce a 10th season of "Cheers." But the Peacock wishes that was its only problem.

Contracts for "The Cosby Show," "A Different World" and "The Golden Girls" - three of NBC's biggest hits - have all expired as well. And producers of those three series are reportedly also asking for tons of money to continue producing the shows.

This comes at a time when advertising revenues are declining and NBC doesn't have a whole lot of money to throw around. And it's a Catch-22 for the network - it can't afford to pay a lot to renew the series, but it can't afford to lose its biggest hits or it will lose even more money.

CBS OPTIMISM: How excited are they at CBS these days? Well, for the first time in a loooong time they're even thinking about finishing the season as the No. 1 broadcast network.

The Big Eye is putting up a strong fight during this February sweeps period - there's a decent chance it might even win. And network programmer Peter Tortorici has even been quoted as saying CBS might beat out perennial champ NBC, which it now trails by just half a ratings point.

He pointed out that seven of CBS' 13 returning series have improved on their ratings from last season, while just six of ABC's 23 returning shows are up - and all 19 of NBC's holdovers are down.

"For a long time NBC has been held up by the performance of certain `linchpin' series - by `The Cosby Show,' `Golden Girls,' `L.A. Law,' `Matlock,' `In the Heat of the Night.' They're all down," Tortorici told the Washington Post's John Carmody.

Among the biggest surprises for CBS has been "Rescue 911," which now regularly appears in the Nielsen Top 30 and has been beating the ABC sitcom "Davis Rules."

"LITTLE MERMAID - THE SERIES": It looks like we'll be seeing more of the adventures of Ariel, "The Little Mermaid," but on television this time.

Disney is developing "Mermaid" as a Saturday-morning cartoon for next season. Ariel and her friends Sebastian the crab, Flounder the fish and Scuttle the seagull would all be on hand, but not Prince Eric - the series will be a prequel to the action in the movie.

I'm not sure if this is good news or bad news. The level of animation on a weekly kiddie show isn't anywhere near the excellence in theatrical films."MERMAIDS - THE SERIES": "Mermaids" didn't turn out to be a big box office hit, but that may not prevent it from becoming a television series.

The comedy-drama about an unconventional '60s mother (Cher) and her angst-ridden teenage daughter (Winona Ryder) is being developed as a CBS sitcom by screenwriter June Roberts. (Another idea that may or may not be a good one.)

No word yet on who might star, but you can bet it won't be Cher and Ryder.