Ah, sweeps. The three times a year network execs treat viewers to above-average programming so their local stations can pull higher ratings (thus helping them earn bigger ad revenues). The Drew Carey Show, for example, is pulling out all the stops: ''We have an episode with a lot of farting,'' says Carey. Here's a whiff of other highlights:

-- NBC When Ewan McGregor (Trainspotting) contacted the ER producers to gush about the show, he didn't have to drop many hints before exec producer John Wells gave him a part. ''It was just a fan call, and we were big fans of his,'' says Wells. In the episode (filmed almost entirely in Chicago), McGregor plays a robber who botches a holdup and ends up taking hostages, including Julianna Margulies' Nurse Hathaway (Feb. 13). For further trauma, NBC also has ASTEROID (Feb. 16 and 17, 9 p.m.), a miniseries starring a giant rock (see story on page 28).

-- ABC In her first TV movie in nearly two decades, Meryl Streep counterprograms Asteroid in ''...FIRST DO NO HARM'' (Feb. 16, 9 p.m.), about a mother searching for a cure for her epileptic son. ''This is something we thought about making as a feature, and we thought seven people would see it,'' says Streep, considered a female-viewer magnet. ''The way to get the largest audience is to put it on TV.'' ABC is also offering VOLCANO: FIRE ON THE MOUNTAIN (Feb. 23, 9 p.m.), with Dan Cortese as a skier at a resort perched on a lava-filled rock. Ed Asner is the cop, Mary Tyler Moore the victim, in PAYBACK (Feb. 10, 9 p.m.), a thriller that pairs the duo for the first time in 20 years.

-- CBS Isabella Rossellini makes another prime-time appearance (she guested on Friends last October) in a two-part CHICAGO HOPE (Feb. 10 and 17, 10 p.m.) as a college prof trying to have a baby. ''I saw her on [HBO's] Crime of the Century and thought she was terrific,'' says exec producer John Tinker. PEARL (Wednesdays, 8:30 p.m.) goes the stunt-o-rama route with three guest stars: Shock-rocker Alice Cooper cameos as a guardian angel (Feb. 12); nearly a third of the Cheers cast is reunited when Ted Danson stars as Pearl's (Rhea Perlman) late ex-husband (Feb. 19); and, speaking of husbands, Danny DeVito (Perlman's real-life hubby) plays a college dean who falls for Pearl (Feb. 5).

-- UPN Trekkers will experience Collective joy when the infamous Borg make their first appearance on STAR TREK: VOYAGER (Feb. 12, 9 p.m.). Resistance is...well, you know.

-- Fox Jodie Foster gives voice to an evil Betty Boop tattoo on THE X-FILES (Feb. 2, 9 p.m.). MELROSE PLACE celebrates its 150th episode with the two-hour ''Great Sex-Pectations'' (Feb. 3, 8 p.m.), with jilted fiances (Jake) and re-re-seduced ex-husbands (Michael). No bombs, however. ''We learned our lesson last year,'' says exec producer Aaron Spelling. John Waters visits THE SIMPSONS (Feb. 16, 8 p.m.) as a gay antiques collector, and on Feb. 23, Frasier's Kelsey Grammer returns as sinister Sideshow Bob, with sitcom brother David Hyde Pierce in tow as Bob's sibling Cecil. ''He's a little more finicky than Bob,'' says exec producer Bill Oakley, ''with the same homicidal tendencies.''

-- Additional reporting by Dan Snierson


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