(Newb poster poking his head in)

Based on your gallery and my limited understanding of 3d rendering, I can't imagine much use for CS3 for you. The huge advantage to me, as a photographer, between older versions of PS and the PS/CSx versions is layer masks, smart objects and non-destructive filters. This, of course, is also ignoring the photo-specific bits that make Bridge, ACR, etc so beneficial for me.
 
Looking at your images, it seems you are basically using PS for final touch up of your work. Unless you're spending a lot of time using custom brushes to add realistic skin tone, filters for motion blur and foreground separation, that sort of thing....then the more advanced versions of PS aren't really going to be worth your time.

On the other hand, if you want to use saturation/blur tricks to enhance your compositions; blur, noise, and skin mottling to add realism, if you want to be able to edit your images non-destructively....then there's a lot of power between the CSx versions and what you're using.

Hrm....I hope that doesn't come across as too critical for my first post.

They had chained him down to things that are, and had then explained the workings of those things till mystery had gone out of the world....And when he had failed to find [wonder and mystery] in things whose laws are known and measurable, they told him he lacked imagination, and was immature because he preferred dream-illusions to the illusions of our physical creation.
      -- HP Lovecraft, The Silver Key