Back when people still sold CDs, Norah Jones and 50 Cent sold a lot of them.

The diametrically opposed artists - she's the preternaturally pleasant soy-latte queen, he's the pathologically belligerent VitaminWater gangsta - each have a new album out today. And it's a safe bet that neither Jones' The Fall (Blue Note ** 1/2) nor 50's Before I Self Destruct (Aftermath ** 1/2) will reach the heights they achieved with their debuts, back before the music business went into free fall.

In 2002, Come Away With Me introduced Jones as a doe-eyed ingenue whose alluring amalgam of laid-back jazz, soul, and country proved irresistible to grown-up music lovers and Grammy voters. It sold 10 million copies, and won Ravi Shankar's piano-playing daughter five golden gramophones.

A year later, Get Rich or Die Tryin' was welcomed as the work of a cocksure rapper engineered for success, a protege of Dr. Dre and Eminem who had absorbed nine bullets in his cartoonishly muscled torso. With finely calibrated menace and a touch of insouciant charm, Get Rich sold 7 million, and stands as a creative high-water mark of late-period gangsta rap.

But while Jones and 50 (born Curtis Jackson) still command large audiences, they've failed to heed the Madonna doctrine that pop-star endurance requires frequent reinvention.

They have diversified: Jones has her country side project Little Willies, and she starred in Wong Kar Wai's art film My Blueberry Nights. Along with his acting roles, Fiddy is a successful businessman who sells everything from cologne to condoms.

Each artist, though, has suffered from musical stagnation. And until now, neither has been willing to do more than tinker with the tried and true. Jones rarely strayed from her snoozy piano bench on Feels Like Home (2004) and Not Too Late (2007). And Fiddy served up blood-and-guts gangsta rap on The Massacre (2005) and Curtis (2007), though many fans felt that the latter found 50 going soft.

So for Jones, at least, it's reinvention time. The signs are everywhere, from the singer's shorter 'do to the credits list, which omits ex-boyfriend Lee Alexander, who loomed large on her prior albums. It does make room, however, for mildly rocked-out (if still typically unhurried) roots-rock collaborations with Okkervil River leader Will Sheff and prolific country-rock songwriter Ryan Adams.

Jones plays more guitar than piano, and The Fall is being hyped as her first rock album. That overstates the case. Sure, these break-up songs occasionally feature aggressive drumming, and they even flirt with funk on "It's Gonna Be." But The Fall is hardly a radical departure.

Even when she's feeling a tad angsty - tossing and turning in the faintly electronic "Chasing Pirates" - Jones can't help but convey a sense of luxurious calm with her gorgeously supple voice. And for all the efforts to alter her approach, down to the cutesy dog-loving closer "Man of the Hour," The Fall still sounds like a slightly soporific Norah Jones album, for better or worse.

The Fall may be half-hearted, but at least it recognizes that it's time for a tweaking. By comparison, Before I Self Destruct is deeply conservative. That's not surprising, considering it's the work of a capitalist whose $20 million take in 2008 (according to Forbes) was a significant drop from the $150 million he made the prior year when he sold his VitaminWater stake to Coca-Cola for $100 million.

Fiddy's Self Destruct strategy is to firm up his base with an album that's harder than anything he's done since Get Rich. That means pitching woo only when necessary and in particularly crude terms, as on "Could've Been You," with R. Kelly. And spending more time making it clear that 50's intention is to "Spread money to my n- and bring death to my enemies."

The uneven results won't win over any new fans. He's overeager to pick fights - with the Game, Jay-Z, or anyone who'll listen. (He's also chimed in on Philadelphia rapper Beanie Sigel's feud with Jay-Z, guesting on the Broad Street Bully's new song, "I Go Off.")

All of this might seem sadly embarrassing. And sometimes it is. "Gangsta's Delight" is uninspired, and the gang-banging of "Crime Wave" and "Stretch" is wearying.

But much of Self Destruct is saved by an infusion of energy from 50, who sounds more vigorous than in years. "Psycho," with Eminem, is can-you-top-this derangement, every bit as catchy and intelligently crafted as it is distasteful. And "So Disrespectful" finds Fiddy exercised by a hypnotic piano loop and the realization that he lives in a tax bracket other rappers can only dream of.

Self Destruct is anything but adventurous - the bullet-taking tough guy doesn't have the nerve to change things up even to the degree that Jones does on The Fall. But it succeeds in delivering the unexpurgated goods to hard-core fans, ensuring that 50's career won't self-destruct anytime in the near future.

Contact music critic Dan DeLuca at 215-854-5628 or ddeluca@phillynews.com. Read his blog, "In the Mix," at http://www.philly.com/philly/blogs/inthemix.