Toni Collette isn’t drawn to conventional parts. The star of such films as "Muriel’s Wedding" and "The Hours" now plays Tara Gregson, a mom with Dissociative Identity Disorder in the new Showtime series "United States of Tara," premiering tonight at 10 on Showtime. "I’m very happy to be in this world because I don’t want to be in the safe story land, anyway. It’s boring," Collette said. "Mental illness, in general, has a certain stigma attached, and the wonderful thing about this show is it goes beyond that and into this somewhat normal family who are dealing with these exaggerated circumstances. Part of the beauty of this family is the fact that they fully embrace what’s going on with Tara. It does certainly bring up the question: ‘What is normal?’ "

The series, from Academy Award winner Diablo Cody ("Juno"), allows the actress to play Tara and her "alters" - stereotypical homemaker Alice, randy teen T and beer-swilling bully Buck. "I was most concerned about Buck. I didn’t want the guy character to be cliched in any way. They do have to be complete individuals and be treated as such. The alters have just as much of a history as Tara does," she said. "But their very existence means that, as wonderful and as colorful as they are, for Tara herself, they create a black hole. Whenever they’re alive, it’s kind of a minus for her."

Collette is aware the show also bears some responsibility to educate viewers about an illness that is misunderstood. "Since the show deals with something quite serious, I wanted to make sure it was rooted in reality and completely respectful of it, which it is. It’s a very complex disorder, and when I was reading the script, I was constantly asking questions. The big thing that people probably don’t know is that everybody who suffers from it has experienced a chronic and ongoing amount of abuse."

This is the Australia native’s first foray into series television. "In film, there’s a lot of waiting around. I really enjoy the pace of working in television," she said. "It feels like a more satisfying day because you get so much done and there are so many true moments that you get to share with the other actors where you stumble upon something that is really raw and real. It was actually incredibly satisfying. I feel in love with the Gregson family."

So in love that she’s hoping for many more seasons. "I am determined to get back there and continue this story," she said. "It doesn’t feel like it’s over at all. It feels like it’s just begun. It was the best job I’ve had in such a long time. I feel so lucky to be a part of it. I really, really love it. I can’t stress that enough."