Michael Richards is coming back to NBC in a weekly series, but not as Jerry Seinfeld's whacked-out neighbor, Cosmo Kramer. Instead, he'll play a bumbling detective stumbling down the mean streets of Los Angeles in a sitcom that's been put on the fast track in hopes of getting it on the air later this season.

Good thing, too, given the wipeout opening numbers on NBC's new Tuesday night sitcom, "The Mike O'Malley Show," and Thursday night's new "Stark Raving Mad."

Richards's series will be produced at Castle Rock Entertainment, which also produced the monster hit "Seinfeld." And three "Seinfeld" writer-producers have been signed to pen the new series. Two of those three were top choices to write that "Seinfeld" spinoff that's also being developed at Castle Rock, the one that would star Phil Morris reprising his role as slick lawyer Jackie Chiles.

Castle Rock President Glenn Padnick insists that getting the go-ahead on Richards's series doesn't preclude doing the "Seinfeld" spinoff.

"It's still a project we intend to pursue," Padnick said. "We have a holding deal with Phil--that's Step 1. The next step is, who's the writer?"

Morris surprised reporters at the summer TV press tour--as well as execs at NBC and Castle Rock--when he mentioned the "Seinfeld" spinoff in passing, during a session for another network. Castle Rock has yet to formally pitch the project, though NBC will be its first stop.

As for the Richards show, Padnick said it'll get on when it's good and ready.

"We don't want to rush it on the air; it's too important to rush on the air just to take a nosedive."

And as for those plum NBC Tuesday and Thursday time slots, Padnick said either would be a mixed blessing. "They're great time slots . . . but they can be traps. Expectations are so enormous that you can get canceled with the third-best rating on television."

Would you call the day you got married your first anniversary?

Of course not!

Even though it marks the start of your first year of marriage?

Ridiculous!

Would you call last week's premiere of "The West Wing" its first-anniversary show?

Don't be silly!

Even though it marked the start of the series's first season?

Forget about it!

Well, then, if you slogged through the 2 1/2-hour "Saturday Night Live" 25th-anniversary special last night thinking you were in fact celebrating the show's 25th anniversary--you got snookered. It's the show's 24th anniversary. The late-night comedy show debuted in October 1975. October 1999 marks its 24th birthday.

"SNL" creator and executive producer Lorne Michaels explained this new math to reporters during the summer TV press tour. He claimed precedent; NBC pulled the very same stunt for "SNL's" 15th-anniversary special--which fell on the show's 14th anniversary.

Besides, Michaels said, that idea wasn't his, it was Brandon Tartikoff's. Tartikoff, considered one of network TV's greatest programmers ever, was president of NBC Entertainment at the time. Michaels says he asked Tartikoff if it wouldn't be better to wait until "SNL's" actual 15th anniversary to air its 15th-anniversary special. Tartikoff said no, according to Michaels.

We can't ask the fun-loving Tartikoff. This past Aug. 27 marked the second anniversary of his untimely death--or, by his own measurement, the third.

"Live With Regis & Kathie Lee" is the big winner in the Washington area's syndicated show shuffle, according to the numbers for the first couple of weeks. The program, which this year moved from Fox's WTTG (Channel 5) to ABC's WJLA (Channel 7) at 9 a.m., has nabbed an average of 87,000 households in the past two weeks--more than double its audience in the same two weeks last year.

"Certain shows belong on certain stations," WJLA General Manager Chris Pike told The Post's John Maynard of the "Regis & Kathie Lee" ratings surge. In Channel 7's case, that means more entertainment programming and fewer "issue" shows in the 9 a.m.-to-noon time slot.

So the newly syndicated "Martin Short Show," on Channel 7 at 11 a.m., is doing better in its first two weeks than the show it replaced, "Maury." "Martin Short" has averaged just over 40,000 homes, but it's getting creamed in the time slot by the "Price Is Right" audience of 100,000 homes on CBS's WUSA (Channel 9).

Queen Latifah, on the other hand, averaged a meager 29,000 homes in the same 11 a.m. berth over at NBC's WRC (Channel 4) in her first four broadcasts. That's a mere 2,000 homes better than "Leeza" logged in the same time period last year and about 14,000 homes shy of Roseanne's talk show average for Channel 4 during the same period last year. WRC is among the NBC-owned stations that decided the "Roseanne" numbers were so weak it'd be better not to air the show even though they had to continue paying for it.

Maury Povich can boast some success with his show's move to Channel 5, where he got his start in the TV business. His 9 a.m. "Maury" averaged 43,650 households in its first two weeks this season; last year it was averaging 34,000 homes on Channel 7. But "Maury" still trails time slot competitor Montel Williams on Channel 9 by about 10,000 homes.

New to Channel 5, "Divorce Court" is averaging about 60,000 homes in two back-to-back airings starting at 10 a.m. Yes, that's better than time slot predecessor "Donny & Marie." But last week "Divorce" got KO'd by WJLA's one-two punch of "Hollywood Squares," which averaged 81,200 homes, and "Family Feud!," with 64,900.

"Judge Greg Mathis" debuted last week on Channel 50, averaging about 32,000 homes--no competition for UPN's "Jerry Springer" audience of more than 62,000 in the 11 p.m. time slot. But Mathis got no help from lead-in "Ricki Lake," which posted only about 19,000 homes.

"Judge Judy" is still the reigning courtroom show. Over the past two weeks, "Judy" has averaged about 112,000 homes in the 5-6 p.m. hour on Channel 5. She finished behind all the local newscasts in the time slot, but they were bolstered by Hurricane Floyd coverage. Last week, sans Floyd, Judy was No. 2 in her time slot, behind only the Channel 9 newscast.