In this post, I linked to a workaround to get the HP Photosmart C3180 to work with Airport Express. The reason that this workaround was need, was because the driver wasn't compatible with remote printing.
Out of curiosity, I decided to download the lastest software for the HP Photosmart C3100 series, and tried to configure remote printing again. Once the new version was installed, printing through the Airport Express worked perfectly. In fact, even high quality photos look good printed this way.