"O" Yes--Omarion No. 1

This album chart is brought to you by the letter O.

Omarion, the first B2K alumnus to release a solo album, is now the first to debut at number one as O topped the Billboard 200 with sales of 180,000 copies last week, according to Nielsen SoundScan figures released Wednesday.

The R&B singer is looking to prove he's not going to be another boy-band casualty. "There is a greater responsibility with being a solo artist than when you're part of a group," says the 20-year-old Los Angeles-based performer. "You can't switch it up or take a breath because all of the focus in on you. It's a lot of work."

Joining B2K at 15, Omarion helped the band score number one singles with "Uh Huh" and "Bump, Bump, Bump" and starred with his bandmates in last year's You Got Served. B2K actually split after the soundtrack's release but before the film opened in theaters.

The week's other major debut came courtesy of Tori Amos. The ever-kooky singer-songwriter seems to take a page from Muhammad Ali's "float-like-a-butterfly-sting-like-a-bee" philosophy with her new, 19-track album The Beekeeper, backed by the lead single "Sleeps with Butterflies." The disc sold more than 82,000 to open at number five and is Amos' fifth Top 10 debut. Amos kicks off a North American tour Apr. 1 in Clearwater, Florida.

Kidz Bop, Vol. 7, the teeny-bop covers series, landed the final Top 10 bow, checking in at number seven with 73,000. The latest installment features kids' covers of Black Eyed Peas' "Let's Get It Started," Usher's "My Boo" and Bowling for Soup's "1985."

With O moving into the top slot, last week's top three discs all shuffled down a spot. Ray Charles' Genius Loves Company and Green Day's American Idiot, both Grammy standouts, dropped to numbers two and three, respectively. Meanwhile, the Game--recently ousted from the G-Unit crew for not backing 50 Cent's beefs with Nas and Jadakiss--slipped to four with The Documentary.

The rest of the Top 10 were also holdovers: John Legend's Get Lifted at six, Eminem's Encore at eight, 3 Doors Down's Seventeen Days at nine and Kelly Clarkson' Breakaway in the 10 spot.

Further down the chart, Truth's Tru beat out Southern-fried rockers Kings of Leon's Aha Shake Heartbreak by a mere 216 copies. Truth debuted at 54, while Kings followed, each selling a hair over 20,000 discs.

Other noteworthy debuts included Layzie Bone & Bizzy Bone's Bone Brothers at 60, the Atticus: Dragging the Lake compilation at 63, Los Lonely Boys' Live at the Fillmore at 69, Thievery Corporation's Cosmic Game at 94 and Chely Wright's Metropolitan Hotel checking in at 96.

Ray Benzino, cofounder of the Source Magazine, continues his attempts to revive his rap career by going after Eminem yet again. His new album, Arch-Nemesis, featuring "Look Into My Eyes"--a repsponse to Eminem's conciliatory "Like Toy Soldiers"--opened at 117.

Starting with the release of Benzino's single "Pull Your Skirt Up," the two rappers have battled back and forth primarily through mixtapes. Eminem has essentially demolished the older emcee, who still won't let the beef go.

Finally, Evanescence's Fallen celebrated its two-year anniversary on the charts this week at 112.

Next week, expect 50 Cent's The Massacre to dominate sales, even though the disc will only be on sale four days, instead of the typical six. (Interscope pushed the album up to Thursday from its release date of Mar. 8 due to piracy fears.)

Here's a recap of the Top 10 albums for the week ended Sunday, per Nielsen SoundScan:

1. O, Omarion
2. Genius Loves Company, Ray Charles
3. American Idiot, Green Day
4. The Documentary, The Game
5. The Beekeeper, Tori Amos
6. Get Lifted, John Legend
7. Kidz Bop, Vol. 7, Kidz Bop Kids
8. Encore, Enimem
9. Seventeen Days, 3 Doors Down
10. Breakaway, Kelly Clarkson