From my understanding, there are a few “lines”, though exactly where it goes depends on who you’re talking to =)
If you don’t have any interest in programming, then I think that “developer” might not be the title you’re looking for, but rather “designer”.
Since you have interest in HTML/CSS from what it seems, I would focus on becoming king at that, IE being able to make fullblown static templates to be handed down to whomever will be coding the underlying structure/functionality.
Outside of pure technology (HTML, CSS, best practices, , etc) I would look into the psychology behind it, so that you can make good UIs that work. Usability, Human-Computer Interaction, etc.
@rdldew – At Unleash (my business) – I do the front end code, HTML/CSS and some basic JS and a tiny bit of PHP – usually the PHP is just related to particular content management systems, like WordPress for example.
If more indepth PHP/JS/programming is needed then I have a backend developer who concentrates on that. So basically we separate responsibility between front and backend development.
Regarding design (photoshop/illustrator work) that is by another person entirely, so we have 3 people on each project working on different sections and responsibilities.
It’s always best to be a master of something than a jack of all trades so I would say to focus on front end development if you’re not keen on learning programming languages.
Another thing that will help getting your foot in the door is showing curiosity and a clear eagerness to learn.
Anecdotal evidence ahoy: I got my current job because when the person asked me if I knew X, and my response was along the lines of “no, where should I start to pick that up?” (I figured I was already screwed =), that’s at least a part of what landed me the job. I’m also good at what I do, etc, but it was the clear willigness to learn that helped me the most.