Absolute paths don't work using in-place server

The problem is simple - when I run a page it shows in the url box on my browser: localhost:63342/<ProjectName>
And when I use an absolute path (a url starting with '/' referring to my site root eg - /images/image.png) it doesn't work. I believe this because it's trying to load localhost:63342/images/image.png instead of localhost:63342/<ProjectName>/images/image.png
How do I get around this? (please don't tell me not to use absolute paths - they're useful)