Cable has made strong gains in viewership and critical attention this year, and the networks are determined to stem the audience defection. To do that, they must alter the perception that cable is where the quality shows are heading.

Reinforcing that perception will be the return of HBO's "The Sopranos" at 9 tonight. If the fourth season of the mob drama is as terrific as the previous three, next year's Emmy race for best actor in a drama could be the first dominated by cable: James Gandolfini for "The Sopranos," Tony Shalhoub for "Monk" and Michael Chiklis for "The Shield."

Cable TV used to have a simple formula: lots of reruns, way too many Clint Eastwood movies, wrestlers wound a bit too tightly, news, music and sports. No surprises, in other words. Not anymore. Basic cable now is attracting more viewers with the kind of original series that big broadcast networks and HBO once monopolized: successful new dramas like FX's "The Shield" and USA Network's "Dead Zone" and "Monk," and MTV's reality/unreality show, "The Osbournes." Cable TV hasn't enjoyed this much buzz about new programs since the early high jinks of "South Park" and "Beavis and Butt-Head."Compared to the usual movie retreads and leftovers from the broadcast networks, cable executives are betting that the new series will help viewers remember their networks in the crowded TV terrain."Original programming helps to differentiate you from the field," says Jeff Wachtel, a programming executive at USA Network. But there are obstacles. New shows are expensive and often unprofitable. Also, there's no guarantee that viewers will latch on to them more than inexpensive reruns.Even so, cable networks have become increasingly willing to spend more on shows that can boost their image.This year, USA Network launched "Monk," a quirky show about an obsessive compulsive detective played by Tony Shalhoub, a respected actor but not a household name. "Monk" did so well that ABC, which passed on the show earlier, decided to air episodes after they appear on USA Network. USA Network also scored with "Dead Zone," about a guy who wakes up after years in a coma and has premonitions. The show's premiere this summer pulled in an audience twice as big as what the network usually gets for its Sunday night time period.Another new show has pumped up FX, which until last spring was a little-known cable channel that featured a bit of raunch and NASCAR. Then it put on "The Shield," a cop show with a lot of attitude and an officer who goes over the edge so much he makes even the good guys nervous.But the biggest success of them all is MTV's "The Osbournes," that stuttering, mumbling, twisted walk through family life featuring aging rocker Ozzy Osbourne. Ratings topped even those for pro wrestling, which used to be the most-watched programming on basic cable.Taken together, this year's crop of series has given cable an extra punch. In fact, "The Osbournes," "Dead Zone" and "Monk" each has pulled in more viewers on average than "South Park" did in its best year on Comedy Central.But when it comes to basic cable, success is relative. Episodes of "Sex in the City" on the HBO premium channel consistently grab far bigger audiences than "The Osbournes," for example.And shows on the big broadcast networks like NBC, CBS, ABC and Fox usually score even higher than HBO's biggest hits. The average audience for Fox's summer hit "American Idol" was almost three times bigger than the top new original series on basic cable. "In terms of the impact on the overall ratings, [the basic cable hits] are not really that significant," says David Poltrack, who heads research for CBS.

A close eye - But broadcast executives are carefully watching basic cable's push to put on better shows."The idea that cable television networks have a significant amount of money to invest in new and original programming makes them more formidable competition," Poltrack says.Cable networks attempted a few drama series in the past -- "Le Femme Nikita" and "Pacific Blue" from USA Network, for example -- but they weren't breakout hits. There's a reason, says USA Network's Wachtel: Most of them weren't very good. But now Americans are more interested in what's on the myriad basic cable channels, which attracted more viewers this summer than NBC, CBS, ABC and Fox combined."It's clearly a different landscape in cable than it was a year ago," says Jack Wakshlag, the head of research at Turner Broadcasting System, which includes TBS, TNT, Cartoon Network and CNN. The top shows on basic cable once tended to be wrestling and movies, but lately those spots have been taken by made-for-TV movies and original series, as well as sports. "I don't think anyone on the broadcast side would have thought that was what was going to happen so quickly," Wakshlag says. Part of it is luck in finding shows that viewers latch on to, he says, but another part is no accident: The big cable networks are following the lead of HBO and spending more money to put on quality shows.USA Network recently increased its spending on new program episodes by about 50 percent. It still isn't shelling out as much per episode as broadcast networks and HBO, but it's getting close, USA's Wachtel says."Dead Zone" and "Monk" each cost about $1.5 million per episode, or about $500,000 less than what it typically costs for each installment of dramas on major broadcast networks.

Not where the money is - New dramas aren't typically big money-makers for cable. They are expensive compared to what it costs to air reruns or old movies. Cable bosses try to trim their losses by airing the shows lots of times. USA, for example, has put each episode of "Dead Zone" on four or five times in a week and plans to rerun the segments later. Cable networks also are at a disadvantage because major advertisers typically won't pay cable networks as much as they pay broadcast networks for commercial time.All of which explains why cable networks are still just dabbling with costly original drama series. "They have to get to the point where they can make money on these shows," says CBS' Poltrack.But by pulling in bigger ratings, cable networks that have hit series are putting pressure on rivals that don't.Two of the biggest cable networks -- TBS and TNT, both based in Atlanta -- have yet to see ratings soar with original series. TNT recently decided not to air a third season of "Witchblade."Brad Siegel, the chief of Turner Broadcasting's entertainment networks, wants two strong series for TNT. He plans to roll out a few original movies as pilots, with hopes that one of them will develop into a series that could launch as soon as late next year.Americans are primed to give new cable dramas a chance, Siegel says."In the past, TV viewers would not have expected to see high quality or broadcast-quality original series on cable networks," he says.But now they do."That playing field," he says, "is getting more and more level every day."