Can I use the Scrum images you have on your website?

You may definitely use the images.  We had the images prepared specifically with the hope that others would use them. In case you haven't seen it, here's a page with variations of Scrum images: 

You may also want to look at:  which is a PowerPoint and Keynote format reusable set of slides for introducing Scrum. This popular presentation has been translated into 19 languages.