"They just made the big plays and we didn't, and that's what the game came down to," Harrington said.
Kevin Williams returned an interception 54 yards for a score on Atlanta's first possession, a play made possible when a quick snap count by the Falcons caught Williams flat-footed and kept him from rushing.
"They were fighting uphill the rest of the day," Williams said.
Antoine Winfield intercepted a pass bobbled by Michael Jenkins and ran it back 14 yards for the final touchdown, less than five minutes after Peterson's clinching score.
Thrust into full duty when starter Chester Taylor hurt his hip, Peterson made an amazing catch out of the backfield that he turned into a 60-yard touchdown reception. He also, by the way, finished with 103 yards rushing on 19 carries.
"My vision is having Chester and Adrian carry it equally," coach Brad Childress said. "Obviously it's nice to have somebody take up the slack."
Harrington? He was actually doing all right, until the disastrous final stretch. But he fell to 23-44 in his career as a starter and didn't do anything to make Atlanta forget about Vick, whose indefinite suspension and probable jail time for his role in a dogfighting ring stunned the Falcons this summer.
"We knew under pressure, he would throw the ball in the air and give us a chance to make plays," Winfield said.
Harrington finished 23-for-32 for 199 yards, but he failed to lead his team to the end zone. He also paid dearly for those two interceptions, even though they weren't all his fault.
"One guy would break down here and one guy would break down there. So it just wasn't all clicking," new coach Bobby Petrino said.
Peterson, the seventh overall draft pick out of Oklahoma, was taken to inject some life into an offense that was one of the NFL's worst last season. He couldn't have been any better in his debut.
With the Vikings clutching a 10-3 lead early in the fourth quarter, Peterson sneaked past a blitzing DeAngelo Hall and put both hands on an off-target pass from Tarvaris Jackson. The ball popped straight up in the air, but Peterson caught it and ran through the secondary without being touched.
Peterson didn't just become the featured back in his first NFL game. He was the lead kickoff returner, and he also saved Minnesota from a dangerous situation late in the first half by falling on a fumble at his 31-yard line after an errant shotgun snap by Matt Birk.
Linebacker Keith Brooking promised a bright future for the rookie, but he blamed the defense for giving up so much on the ground. Hall said he thought the Vikings actually benefited from Taylor's injury.
"Chester's a bit of a smaller back and is not going to deliver the blow like Adrian Peterson did all day today," Hall said.
The Falcons were without defensive tackle Rod Coleman and another starter, free safety Chris Crocker. They forced one turnover in the third quarter, a diving interception by Hall, but moved a measly 10 yards after the possession change and summoned Michael Koenen for his fourth of five punts.
Warrick Dunn, coming off an offseason operation on his back and entering his 11th year in the league, showed he's not slowing down. Dunn finished with 55 yards on 22 carries against the league's best rushing defense in 2006, and he caught four passes for 26 yards.
But the Falcons sure could've used the energy and constant threat that Vick -- for all his faults as a passer -- always provided.
"Do we miss that one guy? Listen, man, we prepared ourselves to move the football. We didn't get it done. You have to tip your hats to the Minnesota Vikings defense," receiver Joe Horn said.
The Vikings certainly weren't perfect, failing on six of nine third downs. Except for Peterson's big play, they kept getting stuck in the middle of the field -- a big reason why they finished 6-10 last year.
Jackson was blitzed a lot, and the Falcons stacked the line without fearing any of Minnesota's receivers. He threw to nine different teammates, finishing 13-for-23 for 163 yards and one touchdown and one interception.
"I thought he looked comfortable back there," Childress said. "I didn't see any jittery-ness."
Matt Prater made a 45-yard field goal for Atlanta, but he missed a 44-yard try in his NFL debut. ... After finishing last season without a sack, Minnesota defensive end Kenechi Udeze got one on the game's final play and was given the game ball for his effort.