I've been involved in an xna project for the past couple of months and I'm upper intermediate in terms of my 3d modeling knowledge. Something that I've been thinking alot about lately is polygon count. I have several models for the project, most done by hand some purchased in interest of time. I've got several done by hand that come out around the 200-400 polygon range, others around the 1k-4k poly mark and a purchased one clocking in originally at 8k but i reduced the polys down to 4k.

My question is what would you say is norm. So far the game hasn't choked but i still havent sat down and done the, load in as many models as you can til it chokes test (other than some original testing where fps dropped to 20 fps when this one model would enter the viewport and jump back up to 200+ when it was gone. Just curious.

The actual number of polys is rather meaningless. It's what you do with them that counts.

The Xbox's GPU is insanely fast at drawing zillions of polygons. Most often, framerates drop due to bottlenecks in the CPU. For example, using BasicEffect is pretty inefficient for drawing many copies of the same model, since it sets renderstates each time you draw it. If you have many of the same model look into mesh instancing.

There are several threads on this already, here's one I found at the top of a search.

When someone says "low poly" they generally mean less than 1k polygons per object (and for a "low poly barrel" it's more like 150 polys :-)
What's at least as important, though, is the number of textures/materials you use on the object. If you can get away with only a single "stitched" texture/material on each object, that object will draw much faster than if it has two or three (or fifteen...) materials/textures.
Note that multiple maps in the same material (normal map + gloss map + diffuse map, say) still count as only one texture/material.
If you can make each object use a single material, then you can throw thousands of polygons at objects that need it, and the Xbox won't particularly mind (assuming the rendering engine is not dumber than rocks).

Thanks, i think that about sums up what I was curious about.