appears that there is a margin setting on the box. does anyone know where to go to edit this
I think you can try changing this
padding: 5px 10px;
padding: 5px 4px;
...but it will affect every sidebar block.
I think the alternatives might be defining a div style in the text widget itself, something like;
<div style="text-align:center;">your content</div>
That may not be effective by itself for centering images,though. "display:block;" comes to mind for some reason, for images, or perhaps just redefining the height and width of the images to fit the constraints of the sidebar blocks would be more effective.