Crosby, Stills, Nash and Young: They came, they rocked, they cleaned their fans' wallets. At the sold-out United Center on Sunday, the legendary quartet offered several decades worth of great songs and a few clinkers. They threw themselves into ragged but passionate performances informed by off-key singing and rip-roaring guitar jousting. And they embraced idealistic sentiments in the lyrics and good old-fashioned capitalism at the ticket windows and merchandise counters.

For anyone who appreciated the change-the-world bent of the collected works of David Crosby, Stephen Stills, Graham Nash and Neil Young—from Buffalo Springfield's "For What It's Worth" to CSNY's "Ohio"—blinders were a necessary accessory at the quartet's second budget-busting reunion tour in three years (they return to the United Center on April 25).

They've become the people they once mocked, multimillionaires who charge $18 for a concert program and $226 for a front-row seat. Were they worth every penny? Depends how much you invested in those old we-can-change-the-world songs in the first place. Now when Stills makes a plea to "feed the people everywhere and let the peace begin" in a new song, who's buying it? Better to address reality: CSNY have become mega-bucks entertainers, just like any Vegas act worth its retainer at Caesars Palace. Make no mistake: They entertain well, playing for more than 3= hours. There was no fancy staging or distracting theatrics, and a more adventurous set list than on any recent Rolling Stones or Who tour.

"We keep writing songs—there's nothing more we can do," Young said. A few fell flat. A pair of post-Sept. 11 tributes—Young's "Let's Roll" and Nash's "Half Your Angels"—sank beneath the weight of their lyrical and sonic clichis (Nash's loungy electric keyboards, Young's hackneyed guitar riff). But Young's "Goin' Home" upheld his legacy for raging, "Hurricane"-style epics, its big doomy guitar chords pounding through the drone of Booker T. Jones' Hammond organ. Young also unveiled some Stax-style neo-soul numbers from his forthcoming solo album, including "You're My Girl" and "Two Old Friends."

The straw-haired guitarist's presence energized everyone on stage, particularly Stills. If Young's solos tend to unwind with a similar slow-burn patience, Stills remains a master of many voices: a fusion of raga-rock and flamenco on "Suite: Judy Blue Eyes," a gleaming blade slicing through Young's jagged barbed-wire tone on "Woodstock," a jazz bassist on Crosby's "Dream for Him."

Crosby and Nash never found a comfortable vocal range for the demanding, quirkily brilliant "Guinevere," but Crosby brought fire to "Almost Cut My Hair" and "Long Time Gone." Nash played cheerleader for the guitar solos, and his nursery-rhyme facility in "Our House" and "Teach Your Children" remains quaintly inescapable.

The foursome buckled down hardest for "Rocking in the Free World." "Don't feel like Satan, but I am to them," Young sang, a line that cut to the heart of the matter. It used to be a black and white world for the socially conscious rock 'n' rollers of the '60s. Now the lines have become blurred, and the ideals of CSNY's youth have taken a few hits on the way to a comfortable retirement.

Crosby, Stills, Nash and Young play the United Center again on April 25.