Apple computer question!

I have a apple laptop and it seems to not be functioning well I think it has a virus. I use it only for work and school so I am not sure why I would get any viruses. My question is if I take it to the Apple Store would they be able to help me take the virus off if it did have one?

By the way I turned off the fire wall so I'm thinking this might have something to do with it. If anyone knows please comment.