Title banner plugin

Hi.

I have created a banner (575 x 175 px) with my company name in stylized text. I want to use this in place of the “site title” text. I want my tagline below the banner. I’m using the Twenty Eleven theme.

Alternatively, the banner could be put in place of the header image, as long as I can still get the tagline. This should achieve the same effect. Although, this method might not allow me to have the search bar in the top right corner.

My Google-fu appears to be inadequate. Is there a plugin(s) that will help me to achieve this? I would prefer not to mess around with php code.

Thanks