Arch joined the cast of MADtv in 1997, as a repertory performer, for the third season. She would be promoted to repertory status mid-season. She is remembered for playing characters like social outcast Susan Whitfield and sassy country gal Wanda Terry-Ann Lainier Parker from the Parker Sisters sketches.

In 2001, Arch's career got a boost when she replaced Annabelle Gurwitch as the hostess of the TBS cooking and entertainment show, Dinner and a Movie. For two and a half years, she appeared, alongside host Paul Gilmartin and chef Claud Mann, in each episode introducing movies and cracking jokes during the preparation of a creative dinner to go with some theme of the movie.

In 2004, Arch's contract had expired. As she was preparing for another season as hostess of the show, she got a call from TBS executives, right after the Thanksgiving holiday, informing her that her contract was not going to be renewed. She left the show on good relations with the Dinner and a Movie staff, but she was very upset about the failure to have her contract renewed. In 2005, she was succeeded by Janet Varney as host.

She has an older brother, Bob Kushell, who is a TV writer/producer and Internet talk show host. Her brother works with her husband, Russell Arch, the Co-Creator and Executive Producer of ANYTIME WITH BOB KUSHELL, an internet talkshow for Sony Interactive's Crackle.com. On September 18, 2007, she gave birth to a son, Garrett Mitchell Arch.