In 2003, she was named one of that year's hottest teen celebrities in the July 2003 issue Vanity Fair. In 2004, Vega finished filming two films: Sleepover and State's Evidence. Then the following year she starred in the Lifetime television film entitled Odd Girl Out as a victim of cyber-bullying. She also filmed for another made-for-TV movie, Walkout. In June 2006, she finished filming Remember the Daze, which was released in limited theaters on April 2007. She also finished filming Repo! The Genetic Opera, which was released in 2008. Vega was confirmed as the lead role in Helix, written and directed by Aram Rappaport, which began filming in Chicago in March 2008. Vega was originally cast in the 2009 Robert Rodriguez film Shorts, however, due to her being in Australia for the filming of Broken Hill, she had to be recast. She was replaced by Kat Dennings. She appeared on Broadway in Hairspray, as Penny. In 2009, she played Ruby Gallagher on the ABC Family television sitcom Ruby & the Rockits, which also starred Patrick and David Cassidy.