Hello Patrick, it looks like you are using the GAME ON theme by Themetree. I don't own that one, but it looks like your logo is too big for that spot and that's why it breaks the style a little bit.
So instead of moving the tabs (it are not single tabs anyway, it is a full menu line), I would suggest moving the logo image above them. Or like in the DEMO use a smaller image for the name of the site and a bigger one in the header background.
Like already said I don't have the theme, so I don't know the code, but I'm sure @Brian A. can help you with this :)