When building web pages, one of my colleagues displays any logo using the CSS background-image property, rather than embedding the image using an HTML t
I generally prefer defining logos in an IMG tag. A simple, practical advantage is that if someone prints your page, the logo will show up, if the logo was set as a background sprite, it would not.
Viewing a site with CSS disabled is helpful when making decisions like this. It gives you a good idea about the lowest common denominator viewing experience of your site. If your site make sense under those circumstances, it's like having your house built on rock.