Now this - THIS - is why I'm willing to pay for premium channels. Because Sunday night, Showtime unveils a superb new series, United States of Tara, in addition to bringing back Secret Diary of a Call Girl and the final season of The L Word. And down the dial, HBO begins new seasons of Big Love and Flight of the Conchords.

You're just not going to find that many quality programs anywhere else.

Let's begin with Tara, which tells the story of a woman with Dissociative Identity Disorder - multiple personalities - and her long-suffering family. She's just gone off her meds, which has meant the reappearance of her alter ego, or "alters" - either T, a randy teenager; Alice, a happy homemaker; or Buck, a profanity-spewing trucker type - every time she's stressed. With an unhappy teenage daughter, Kate, in the house and a sister who thinks Tara is just pretending, there are triggers at every turn. (The rest of the family includes faithful husband Max and gay teen son Marshall, who's extremely protective of his mom.)

Kind of a sitcom, sort of a drama, Tara may be the most unsettling show on TV since Wonderland, the 2000 ABC series that was set in a mental hospital. Watching Tara made me happy and jittery - and I couldn't wait for the next episode.

Tara comes from Diablo Cody of Juno fame (Steven Spielberg is an executive producer), and she has an uncanny knack for finding calmness and rationality in painful situations. Cody had many ways to play Tara's story wrong, but she found the right one. That is, straightforward, without sentimentality or fear or turning the story into what Tara's daughter calls "a Lifetime tampon movie." Like real life, United States of Tara has laughs, heartache and everything in between.

To present this properly, it helps to have a perfect cast. Toni Collette (The Sixth Sense, Little Miss Sunshine) disappears into each alter ego completely and convincingly, and she plays Tara with the requisite confusion and empathy. John Corbett, too, is wonderful as her ever-patient husband. Corbett, of course, has a history of playing the calm inside the storm - on Northern Exposure and, more expertly, in Sex and the City. Though this role is nothing new for him, he manages to make it fresh.

Tara describes having multiple personalities as being "like hosting a kegger in your brain - only you're passed out while everyone else is trashing the joint." Her son says she's what makes the family interesting. But there's more to this story than the alters. Kate's boss, at the restaurant where she works, is quietly, hilariously oily, and the church-going guy Marshall has a crush on is either interested or setting him up for humiliation. It's hard to tell which, but I'll be sticking around to find out.

Prior to the premiere of Tara, the sixth and final season of The L Word begins with a death, then flashes back three months to show what led up to that tragedy. This show about a group of lesbian friends and lovers has always felt like a big, messy soap opera, and nothing in the season opener changes that approach. But fans will enjoy the way series creator Ilene Chaiken has chosen to have her characters say goodbye. Following Tara, the second season of Secret Diary of a Call Girl finds Belle (Billie Piper) still trying to have a normal social life, training a new girl named Bambi to become an escort, considering breast augmentation surgery and dealing with the angry wife of a client. I have to admit, I shied away from this British import in its first season because, well, if I wanted to watch prostitutes, I could turn on HBO's Cathouse and see real pros in action. But selling sex is only part of what this series is; it's more about someone trying to understand love apart from sex. Kind of a Sex in the City of London. And that's worth exploring.

Over on HBO, the polygamist world of Big Love returns for a third season with Bill (Bill Paxton) in hot pursuit of Ana the waitress to be his fourth wife. This requires a bizarre ritual in which Bill and his three wives all go on "dates" with Ana. In the meantime, Roman, the leader of the polygamist compound, is still manipulating events, albeit from prison, and Nicki has a new job that allows her to aid Roman in his defense. Big Love is extraordinary on many levels, the main one of which is how completely straight this utterly abnormal situation is played. Bill and his wives - played by Jeanne Tripplehorn, Chloe Sevigny and Ginnifer Goodwin - create the illusion of a happy, loving, religious family without the slightest hint of irony. In a tangled situation like this, that's impressive.

As for Flight of the Conchords, when we last saw the singing duo of Bret and Jemaine, Murray had saddled them with a third member, who quickly went solo and had a monster hit song. The New Zealanders and their manager deal with the fallout from that move as the second season begins. As usual, they pull this off with a maximum amount of deadpan humor that recalls Abbott and Costello (they are, after all, two poor guys living in a city among exceedingly wacky people), though without the yelling and slapping. In the second episode this season - an absolute classic - Bret buys a $2.79 coffee mug so he and Jemaine no longer have to share one cup. This creates a financial calamity that ultimately lands the pair in jail. In between, there's prostitution, bad concert reviews (written by their manager, no less), an Internet scam and one outrageously funny song about Jemaine's "sugar lumps." Hilarious and ingenious.

What these five shows have in common is what they're not. They're not about cops, doctors and lawyers. These characters are landscapers and hardware store owners and artists and musicians and call girls. The plots are less about work than they are about friends, family and life. None of the characters has supernatural powers (although Belle the prostitute probably does some magical things for her clients). In a sense, they're smaller shows than you'll find on a network. But the characters are more interesting and relatable. And that's worth paying for.