full of respect for peoples time and work I see. People upload so that others can view, not steal and use. that's why the artists will usually ensure their images are covered by a creative commons agreement or a reserved rights.
might I suggest you read the below link and respect whichever commons the artist has attributed to his or her work.
http://www.flickr.com/creativecommons/
if they have an All Rights Reserved on their images, respect that too.
http://en.wikipedia.org/wiki/All_rights_reserved
there's your lesson. now go and learn it. just because a digital image isn't physical in digital form does not mean it isn't stealing. Most good artists will have a way for you to purchase their images. contact them and ask. it doesn't take much effort.