Single column galleries

Hi,

I want to include a Testimonials page on my site. The testimonials will be uploaded images of letters people have sent us. If I upload images using the standard WordPress gallery there is a minimum of 2 columns, which makes the letters to small to be readable.

Is there a Plugin that i can use that will let me install images in one column on the webpage? I have had a look but none of the Plugins specify if they allow for one column.

Plus if I install a gallery plugin will this mess up and rearange my already installed images on my website?

Thanks