It's no surprise Just Like Heaven was the number one movie this weekend. It's smart, funny, and it's got two great actors in the lead roles - Reese Witherspoon and Mark Ruffalo.

We sat down with Mark, who we're so used to seeing in thriller's, but has become the new romantic comedy star. He said he's had enough of this genre, but he really liked this film.

This is what he had to say:

Is this a genre you feel more comfortable working in?

Mark Ruffalo: No, it's not my favorite genre but I wanted to do it. I was hearing around town that I couldn't do it – Mark Ruffalo can't do comedy, Mark Ruffalo can't do a romantic lead – and so I was like ‘those are fighting words my friend and so I did a couple little things. This was it though, I'm ready to go back; I'm going to do Zodiac now.

Why this particular one?

Mark Ruffalo: I liked the story of it, the themes of it. And as we worked on it, I felt it was kind of like the anti-romantic comedy a little bit. Everything's played really real; everything's shot dark, you open up with a characacter who's deeply depressed, and slightly marginalized. He's not your classic leading man in a romantic comedy. Then we get into the love story which I feel is handled really honestly; I think it's actually funny and romantic, unlike a lot of romantic comedies. It actually delivers on what it promises to do.

Do you believe in the afterlife?

Mark Ruffalo: I don't not believe; I don't dwell too much on it or have a solid knowledge about it.

Was there a difference of your shooting style compared to Reece's?

Mark Ruffalo: I never noticed anything; I probably have a more tortured way of working and so I appreciate the ease that Reece comes along with.

How was it working with Reece, and did you guys go over the script before shooting?

Mark Ruffalo: It took a while; it's a style. He believes he is seeing this thing, it's as real as you sitting in front of me. It's pretty much the same as I would work with anyone. The problem is when you're in a group of people and you're doing that, how do you not make the rest of the group think that you're not totally out of your mind an so that was a big problem for me – how to make that stuff work.

Was it difficult to make that transition to when she was there and when she wasn't?

Mark Ruffalo: Yeah, I shot the movie twice. At first, they had a ping pong ball or a tennis ball hanging for where my eye line would be and then after a while I could do it just from hanging out with her; I can do it right now. And so naturally, I just fell into the rhythm.

What are you working on right now?

Mark Ruffalo: I'm doing Zodiac with David Fincher. There's a movie I want to make and direct; it's about a guy in a wheelchair who's a son of a bitch, a paraplegic, a selfish guy, played by a real paraplegic. It's hard to get a movie like that made; no one wants to see a son of a bitch in a wheelchair. And it's hard to raise money for a movie like that and there's not a lot of actors like that. It's a guy I grew up with; a guy in my school had a awful climbing accident and he lost the use of his legs. He wrote this beautiful script so he's going to play the title character. We're plugging along; it'll get made in the next couple of years, I expect that. If this movie (Just Like Heaven)does well, I can get it made.

Can you talk about your character in Zodiac?

Mark Ruffalo: Yeah, Dave Tosky, he's SFPD (San Francisco Police Department), head inspector of the Zodiac killer on a particular case. He's a great family man who's caught in this crazy case that's in five different counties. This guy was destroyed by looking for the Zodiac killer and he sort of rises back up at the end; it's like going back to the In the Cut type film.

What's a Fincher set like?

Mark Ruffalo: David said this movie is all about behavior and not about the shot. We're shooting on digital video and long dialogue scenes so there will be all acting in it.

How was shooting by yourself in the bar scene?

Mark Ruffalo: I worked with a clown from Cirque Du Soleil, and we did a lot of clown excersises, body isolation, and to figure out how to use it correctly. I'd like to do more physical comedy.

If you could jump into anyone's body and control them, who would it be?

Mark Ruffalo: George Bush.

Just Like Heaven is in theaters now; it's rated PG-13.