I think Pingdom Tools gives you a false image. I opened your website (advia.com.au?) in Chrome with the Developer Tools open, and it loads 57 items, not 146 as Pingdom Tools shows. I think Pingdom Tools just scans the HTML and CSS files and loads all images it finds there – you have 113 url() references in your screen.css file for example (click on “Show link hierarchy” to make this clear in Pingdom Tools). Most browsers will only load these when they are needed.
