Nevertheless, good graphics and page design can grab the viewer's attention, and may well make the difference between being bookmarked, and being forgotten - even if your content is brilliant. Don't link directly to images on another server unless specifically asked to do so. Here's a comprehensive example of an image tag. The height and width attributes allow browsers to layout the page while the image is still downloading, and avoids that the text 'shuffles about' as the images come in.
Graphics can be very easily overdone.
On the other hand, a site with nothing but text is unappealing to most of us. Some images look better if their background color matches the browser window, making the image appear to float in the window. You can't do this by setting the background color of the image, since you can't control how people will configure their browsers. You can control this by using GIF89a images, which have the ability to mark a single color in the colormap as transparent, forcing the browser to use its background color for those pixels in the image. Anti-aliasing is a technique used in graphics construction to minimise the 'jaggies' that you can see on lines that are not perpendicular or horizontal.