Kris Allen and Adam Lambert join a select group of individuals after this season of American Idol. The question now is: How will they do in the future? We take a look at previous contestants to gauge a prediction.

THE WINNERS

Season 1: Kelly Clarkson

Since winning the show in its inaugural season, Kelly Clarkson has become one of the most successful pop singers of the 21st century. Post-Idol hits like “Miss Independent,” “Since U Been Gone,” “Because of You,” and the recent “My Life Would Suck Without You” have helped cement Kelly as the most successful Idol contestant around the world.

Season 2: Ruben Studdard

After winning by the closest margin in Idol history, Ruben Studdard’s career has seen some interesting turns. Sales for his debut album, Soulful, were successful, but after disappointing sales for his third album, The Return, he was dropped by Arista Records. Ruben remains signed to Idol producers 19 Entertainment, and just released a new album.

Season 3: Fantasia Barrino

Following her Idol win, Fantasia dropped her last name, recorded two best-selling albums, and ventured into other entertainment areas, including penning an autobiography, Life is Not a Fairy Tale and starring in the Lifetime adaptation. She also auditioned for the role of Effie in Dreamgirls, losing out to fellow Season 3 alum Jennifer Hudson.

Season 4: Carrie Underwood

While Kelly Clarkson may be the most successful Idol winner, Season 4 winner Carrie Underwood is quickly closing in on her for being the biggest Idol success story in the United States. Carrie is the current reigning queen of country music, with nearly 10 million albums sold, a string of #1 country hits and enough awards to fill a museum.

Season 5: Taylor Hicks

After his win in Season 5, Taylor Hicks released his self-titled debut album in the fall of 2006 – and within a year, became the first Idol winner to be dropped by both his record label and 19 Entertainment. Taylor is currently in the touring company of Grease and just released his sophomore, independent album, The Distance.

Season 6: Jordin Sparks

Following in the pop success of Kelly Clarkson, Jordin Sparks became the first Idol winner ever to have her first four singles chart in the Top 20 of the Billboard Hot 100. Her song “No Air” became one of the most-played songs of 2007. Jordin is now preparing for the launch of her sophomore album, Battlefield, with the title track climbing the charts.

Season 7: David Cook

After a year, David Cook’s career is just starting to rise. His debut album, David Cook, has sold over a million copies, and his touring sales are starting to explode. His debut single, “The Time of My Life,” spent 14 nonconsecutive weeks at #1 on Billboard’s Hot Adult Contemporary Tracks chart, and he recently charted his sixth Top 40 single with “Permanent.”

Season 8: Kris Allen

Following the season finale, Kris Allen debuted five singles on the Hot 100 charts, including two in the Top 20 – his debut single, “No Boundaries,” as well as his cover of Kanye West’s “Heartless.” Kris also debuted in the Top 50 of the Billboard Top 200 with an iTunes-exclusive collection of his American Idol songs.

THE RUNNERS-UP

Season 1: Justin Guarini

Unlike winner Kelly Clarkson, as well as future runners-up, Justin Guarini was unable to create an identity apart from American Idol. His debut album, Justin Guarini, flopped – in part due to the gap of time between the season’s end and his album’s release. More recently, Justin has worked with TV Guide on – what else? – their coverage of American Idol.

Season 2: Clay Aiken

While Clay Aiken may have placed second to Ruben Studdard in Idol’s second season, he managed to become the third-highest album-selling Idol contestant of all time. In the past few years, though, his popularity has waned. He recently had a son via surrogate and, after years of speculation, publicly acknowledged his homosexuality.

Season 3: Diana DeGarmo

While she seemed to disappear more than most Idol runners-up after her debut album bombed, Diana DeGarmo has managed to build a successful career on Broadway. DeGarmo, a Georgia native, also competed on CMT’s Gone Country recently, and is working with country star John Rich on her country music debut.

Season 4: Bo Bice

Season 4 runner-up Bo Bice initially managed to do pretty well in his post-Idol career, though he was ultimately dropped from his record label when his sales were less than anticipated. His sophomore album, self-produced and released independently, garnered Bo more critical acclaim – and lower sales.

Season 5: Katharine McPhee

While in most seasons, the winner gets the lion’s share of promotion, Katharine McPhee managed to get more attention than winner Taylor Hicks. After working with him on American Idol, pop producer David Foster has worked to ensure Katharine stays in the spotlight. Katharine’s self-titled debut gave her a Top 40 single with “Over It.”

Season 6: Blake Lewis

Critics assumed, after he lost to Jordin Sparks, that Blake Lewis would prove to have the more successful career. Unfortunately, an unchecked ego produced both one of the more interesting post-Idol debut albums in Audio DayDream and a tendency to come off as…less than professional during promotional tours. Blake is currently a freelance artist.

Season 7: David Archuleta

After a year, David Archuleta’s career is also taking off. The debut single from his self-titled debut album, “Crush,” debuted and peaked at #2 on the Billboard Hot 100 last fall, giving him the highest debut of any single in 2008. Archuleta is now touring with teen star Demi Lovato and working on a follow-up pop album and a Christmas album.

Season 8: Adam Lambert

Adam Lambert debuted four singles on the Billboard Hot 100 following the Idol finale, including garnering a Top 20 hit with his version of Tears For Fears’ “Mad World.” His collection of Idol songs for iTunes debuted at #33 on the Billboard Top 200 chart – outselling both winner Kris Allen and former Idol Ruben Studdard’s new album, which bowed the same week.