I like the scene, but it's really not that huge. The objects used aren't high poly at all and the textures are rather small also. Those objects were designed  with huge scenes. While it looks impressive and huge, it;s actually quite less demanding on a computer then a few fully clothed & textured figures with some high resolution hair in a scene.

I've attached my city that I did quickly in Poser Pro on my machine, used FireFly with medium settings (right between Draft and Final, I most often use that setting). Qood qoality, yet reasonable renderign times as well. I've got 2Gb installed and I'm on winXP.

As you can see Poser is very capable of handling a similair scene as whay you did in D/S. I may post a different angle also, not sure yet, got to find some time first ;-)

Artwork and 3DToons items, create the perfect place for you toon and other figures!

http://www.renderosity.com/mod/bcs/index.php?vendor=23722

Due to the childish TOS changes, I'm not allowed to link to my other products outside of Rendo anymore :(

Food for thought.....
https://www.youtube.com/watch?v=pYZw0dfLmLk