"I just can't believe I get to be part of this new world!" enthuses fashion's latest designer, Gwen Stefani, on the long-anticipated launch this week of her contemporary line, L.A.M.B.

Buyers will finally get to review- and write- orders for the line today in its New York showroom, following a tease Monday afternoon during a personal appearance by Stefani at Macy's Herald Square and another later that evening at a bash hosted by LeSportsac, which does the L.A.M.B. bag line. Considering the phenomenal success of her collarboration with the bag brand, L.A.M.B. apparel could prove another hit for one of pop music's biggest superstars. Her clothing line alone is conservatively expected to generate first-year sales of $20 million.

"It's all so weird it got to this point. I can't believe I have a book full of designs. I have samples. I have a showroom in SoHo. I've been fantasizing about this for a long time," said Stefani.

Longer, in fact, than the year or so since the idea to materialize her much-photographed, much-analyzed and much-copied personal style into a commercial brand began leaking in gossip columns and buzzed about on No Doubt chat boards. In fact, Stefani has been dreaming about this since she was a kid.

There were all those trips with her mom to the House of Fabrics near Stefani's suburban home in Anaheim, Calif., where the band she co-founded in 1987 took shape under the shadow of Disneyland. There were the dresses she cut and sewed herself before heading out on her first club tours.

Even once the ball appeared to get rolling on the L.A.M.B. venture, plans for a fall debut at retail fell through as it hit all those normal delays involved in getting any new company off the ground-securing the right team, 15-hour days spent learning an entirely new industry, etc. But they all proved a "blessing in disguise," Stefani admitted. "I was so happy because I actually got to draw the collection. I feel like I really know what it takes. I drew every stitch, every seam. I did all the fittings. The amount of time and effort I put in is mind-blowing to me. The future scares me because it never ends. This is my baby."

Opting out of fall had other challenges, too. "With spring, it was hard because I don't wear many pastels. So my whole inspiration is the reggae, rock-steady vibe- red, green and gold. You know, those Jamaican Rastafarians don't wear pink."

Still, cuteness is behind the name- what Stefani used to call her tiny snow-white Lhasa Apso. In its memory, Stefani began calling her friends by the cherished pet's name, and it only seemed fitting to use it for her new pet project.

And what a year of projects it's been for the 33-year-old rock star. As the fashion venture took shape, Stefani developed two collections for LeSportsac; took up acting ("I just finished the Scorsese film, "Aviator," and it was an unbelievably amazing experience," Stefani said of her turn as Jean Harlow); went back in the recording studio with No Doubt to work on a greatest hits album, which will include a new song or two, and began work on her first solo effort, a dance album she hopes to have ready by L.A.M.B.'s first possible runway show in February 2004.

Oh, and she also managed to tie the knot with longtime love Gavin Rossdale of the Brit-rock band Bush- not once, in a custom Christian Dior gown made for her by her friend John Galliano, but twice, for the benefit of friends and family in England and Southern California. "Can you believe our one-year anniversary is already this week?" Stefani demanded. "This year has been just crazy and exciting. I don't know how I'm doing it. I don't know how I got all these opportunities."

With the Rossdales splitting their time between London and Los Angeles, Stefani looked to the native style in both cities- which resembles her own. The inaugural collection contains chic silk blouses, gingham Marilyn Monroe halters, ladylike dresses cut in jersey and cotton, slim herringbone twill balloon pants and a peplum jacket. Denim ranges from basics to "rock-star" versions. Retail prices run from $40 for T-shirts and $128 to $325 for jeans to $178 to $300 for pants and $250 to $310 for dresses. "You know, hyperstylish comfort pieces you could wear every day."

Details drive its sensibility. There are extralarge gromlets and red, gold and green triple-stitching, and strategically placed safety pins or zippers. A pair of microsanded cotton mechanic pants is ruched. And, to fill the void for not offering accessories- which Stefani personally can't leave home without- there are charms in the shape of lambs and other symbols dangling from tops. Lyrics she wrote and recorded appear on the lining, across slim-cut men's shirting and T-shirts. Stefani even penned a "Once Upon A Time"-type tale about her late pup that appears in a handwritten script throughout the collection.

While Stefani is on many of the Love-to-Dress lists of other designers, she's stumped when it comes to her own wish list. She's already passed along samples that didn't make the finished collection to pals Cameron Diaz and Drew Barrymore. "Really, the biggest problem I'm going to have is seeing other people wear the clothes. I've already experienced it with the bags. I saw a girl with my bag and it was terrifying to see something I came up with on a total stranger," said Stefani. "It's different from someone liking your m