The red-hot sci-fi show "Roswell" has often been referred to as "Buffy the Vampire Slayer"... with aliens. Fair comparison?

"It's not, really," argues series co-star Katherine Heigl. "I love 'Buffy.' It's a great show, but I think it's more action-oriented and there's a lot more supernatural stuff going on. It sounds bizarre to say, because 'Roswell' should have a lot of that too. But one week on 'Roswell' can be totally normal, with nothing alien going on. We can be doing high school stuff. Then, the next week, we'll get a fourth alien visiting or FBI agents chasing us. We've got a really good mix of high school drama and 'The X-Files.' On 'Buffy,' she's got some strange demon to fight every week. Our show is different from that, and a little tamer."

Heigl plays Isabel Evans on Roswell, which follows the adventures of three aliens living on Earth as human teens. There's Isabel, who's full of attitude and just wants to fit in; Max (Jason Behr), Isabel's brother, who's in love with Liz (Shiri Appleby), a human; and Michael (Brendan Fehr), Isabel and Max's alien friend. The FBI, not to mention assorted alien hunters and the town's sheriff, are all closing in on the trio.

Every few weeks, Isabel discovers a new power. Recently, for example, she entered someone's dreams. But the 20-year-old actress wouldn't want supernatural powers like Isabel's.

"It seems almost as if it would be more of a burden than anything else," Heigl says. "It would be something I'd continually have to hide. I'd be one of those people who'd want to run out and part the skies if I could. So, I feel bad for Isabel, Max and Michael.

"They don't even know the potential of their powers. They don't know how much they can do because they've never really been able to use their powers. ... It would be hard for me to hold it in and not just explode."