Four new albums bow at the top of The Billboard 200 this week, led by the chart topping debut of the ninth volume in the "NOW! That's What I Call Music" compilation series. The 20-track Universal/EMI/

Four new albums bow at the top of The Billboard 200 this week, led by the chart topping debut of the ninth volume in the "NOW! That's What I Call Music" compilation series. The 20-track Universal/EMI/Zomba/Sony set -- which features songs by Pink, Britney Spears, Ja Rule, and Aerosmith, among others -- sold 420,000 copies, according to SoundScan, easily besting the 223,000 units sold by R. Kelly and Jay-Z's No. 2 arrival, "The Best of Both Worlds" (Jive/Roc-A-Fella/Def Jam). The pair's collaboration also arrives at No. 1 on Billboard's Top R&B/Hip-Hop Albums tally.

While the 420,000 units moved by the latest edition in the "NOW!" series is indeed an impressive number, it marks the lowest first-week total by a "NOW!" album since the fourth volume entered the chart on sales of 320,000 units in 2000. The last two entries in the series posted first-week numbers that were safely above the 500,000 mark, while the seventh set holds the largest first week sum with 621,500 units in July of last year.

Considering that R. Kelly's last Jive album, "TP-2.com," blasted to No. 1 with 543,000 units in November of 2000, and Jay-Z's last studio set "The Blueprint" (Roc-A-Fella/Def Jam) shot to the top of the chart with 427,000 units last September, the 223,000 units moved by the much-hyped "The Best of Both Worlds" is a rather lukewarm opening. Of course, numbers have been tepid all year, as CD sales are down nearly 8% compared to last year, but "Best" has thus far lacked a blockbuster single. "Get This Money" is at No. 54 on Billboard's Hot R&B/Hip-Hop Singles & Tracks tally, and the set has been plagued by largely negative reviews.

Landing right behind R. Kelly and Jay-Z at No. 2 on the R&B/Hip-Hop Albums chart is newcomer Glenn Lewis with "World Outside My Window" (Epic), which debuts at No. 4 on The Billboard 200. His "Don't You Forget It" is No. 13 on the Hot R&B/Hip-Hop Singles & Tracks tally. Lewis' 86,000 units weren't enough to beat the Lost Highway/Mercury soundtrack to "O Brother, Where Art Thou?," which slides two positions to No. 3 after selling 132,000 copies. The bluegrass and roots music set is No. 1 on Billboard's Top Country Albums tally for a 30th non-consecutive week.

Back on The Billboard 200, laid back pop crooner Jimmy Buffett arrives at No. 5 with "Far Side of the World." Released on his own Mailboat label, the album's 79,000 unit total doesn't quite best the 100,000 copies his last studio album, "Beach House on the Moon" (IDMG), moved in its first week in 1999. Still, it's his highest chart position since 1996's "Banana Wind" (MCA), which opened at No. 4.

Other Billboard 200 newcomers this week include the techno-rap soundtrack to "Blade II" (Immortal/Virgin) at No. 26, imprisoned rapper Ol' Dirty Bastard's "The Trials and Tribulations of Russell Jones" (Riviera/D3) at No. 33, former Savage Garden principal Darren Hayes' "Spin" (Columbia) at No. 35, and Ann Nesby's "Put it On Paper" (It's Time Child/Universal) at No. 62.

Last week's top entry, the self-titled debut from boy band B2K, took a 42% sales hit, and tumbles 2-12. The album continues to perform strongly in urban markets, falling 1-3 on the Top R&B/Hip-Hop Albums tally. B2K's "Uh Huh" slides a little on the Hot 100, dropping 55-62.

John Mayer's "Room for Squares" (Aware/Columbia) jumps 82-56 on The Billboard 200, a 36% gain in its 13th week on the chart. The major-label debut from the singer/songwriter received a boost following Mayer's appearance last week on "The Tonight Show With Jay Leno." Maxwell's "Now" (Columbia) shoots 108-80, on a 35% sales increase. His cut "This Woman's Work" has been steadily gaining spins in urban markets, and holds at No. 19 on the Hot R&B/Hip-Hop Singles & Tracks roundup. "Now" soars 37-27 on the Top R&B/Hip-Hop Albums chart.

Ruling the Hot 100 for a fifth-straight week is Jennifer Lopez's "Ain't It Funny" featuring Ja Rule, fending off a 5-2 scoot from Fat Joe's "What's Luv?" featuring Ashanti. The latter singer once again scores the Hot 100's fastest-growing track at radio with her own "Foolish," soaring this week 9-4.

Ashanti's "Foolish," in fact, settles in for its second-straight week atop the Hot R&B/Hip-Hop Singles & Tracks chart, where Usher's "U Don't Have To Call" receives a 3-2 bump.

The Hot 100's fastest-growing track at retail is 'N Sync's "Girlfriend" featuring Nelly, which skips one slot to No. 5. Meanwhile, the Goo Goo Dolls' "Here is Gone" rockets 44-26, while P. Diddy's "I Need a Girl (Part One)" featuring Usher and Loon climbs 49-24.

The top debut on the Hot 100 is Steve Azar's "I Don't Have To Be Me ('Til Monday)" at No. 73. Other notable entries include Alicia Keys' "How Come You Don't Call Me" at No. 74, George Strait's "Living and Living Well" at No. 75, and Cher's "Song for the Lonely" at No. 85.

On Billboard's rock airplay charts, P.O.D.'s "Youth of Nation" enters its second-straight week at the top of the Modern Rock Tracks tally, and Puddle Of Mudd's "Blurry" begins its eighth-straight week in charge of the Mainstream Rock Tracks chart.