Reality Factory

I've been playing around with google sketchup and I really like how easy it makes modeling a building. So I've converted a model over to both a blender compatible format (which i haven't really learned how to use yet) and a milkshape format. So now I've got the model in milkshape and I'm noticing that the inside of any shape has faces both facing outward and inward. I was wondering if I should be worried about this? the faces are textured and everything. I'm thinking it would frig with rendering but I'm not sure.
What do you guys think?

You need to find a Flip Normals button. Not sure what it is in milkshape. Blender is just pressing N once or twice, I THINK.

In milkshape its go to face->reverse vertexorder or use hotkeys ctrl+shift+F

Ok well flipping the normals didn't seem to give me the desired effect. I've attached the model below for you to look at (if you would please) Flipping normals seems to have an effect yes... but I'm not sure exactly what it does to this particular model. Could you please take a look and let me know if this model is stable and usable for this.
Thanks,
Madness

You need to select the faces that have inverted normals before you use the flip normals tool