's a nice concept, I'll give you that.

Needs a helluva lot more polys, though. Add details, to break up that big grey texture, and to smooth it off around the edges. At the moment it looks like it was hewn rather than built!
You could make the front "hammerhead"-type bit curve down like the engines, and add some superstructure to the spine of the ship and the front hull. Add some stuff to the engine nacelles to make them less prism-like. Then make the turrets a bit smaller and shorten the barrels. Also, the ones on the front just need to be little disc-like shapes, not huge cylinders.
If you want to try 3DS Max, then download GMax from
www.discreet.com. It's pretty much the same (so I'm told - I haven't used 3DS Max), but without the rendering functions.
