Those last shots you posted, there's no detail! Take for instance that, shot with the zombie, why not lay some boards or debris on the floor, or perhaps even remnants of the "party" (Same could go for that first room)
My only other criticism is that all the lights are the exact same color. Add some different variations (like maybe a lantern giving off deep yellowish/orange light. Maybe windows that let in the bright bluish moonlight)
And if you are running out of system memory, one trick that worked for me, is changing the option "Systemmemorycapoff=0" to "1"
That raised my cap from about 1.5 Gigs to roughly 2.4. Can't say for sure it will work for you, I'm pretty sure that it obviously depends on how much memory your computer really has.
Hope to see more from you