American Beauty star Thora Birch says she was ready for something different when she took on the role of Empress Savina in the fantasy film

Dungeons &#038 Dragons (opening Friday). What she wasn't prepared for, she tells TV Guide Online, was dealing with the movie's rabid sci-fi following.

"Sometimes, the fans will ask, 'Do you have a boyfriend?,'" says the 18-year-old actress, who's been working the sci-fi conventions to help promote the movie. "One time I got a gift, an Oogie Boogie man from the movie The Nightmare Before Christmas, and on the tag the guy had put his phone number down!"

When Birch first agreed to do D&#038D, she had just finished playing Kevin Spacey's moody daughter in American Beauty and was having a hard time shaking the role. "It was very easy for me to sort of stay in that depressed funk I had worked myself into," she says. "I wanted something that would kind of snap me out of it and that was extremely different from American Beauty. The character I play in [D&#038D] is the most optimistic person on the planet!"

Despite her enthusiasm for the project, the actress admits it wasn't easy adjusting to all the special effects. The movie features more than 500 digitally enhanced sequences, ranging from flying dinosaurs to epic otherworldly battles. "It was kind of a cinematic culture shock for me," she says. "Working with a blue screen is a pain in the butt. No matter how many pictures they show you of what you're supposed to be looking at, there's nothing that can make me afraid of a blue piece of paper."

Next up for Birch is a starring role in Ghost World, a quirky dark comedy about life after high school based on the Dan Clowes comic book. Also watch for her in the upcoming psychological thriller, The Hole, about four teens who reach a scary fate in an abandoned bomb shelter. Says the former child star: "I want to do as many different roles as I possibly can."