Torians or Drengins always win on normal difficulty level.

I find that any level below about intelligent is a little easy due to very predictable AI behvior. Alot of it hinges on rapid expansion and what some might call the "starfighter gambit" Basically it works like this. Click the button to bring up your military graph. The goal is to keep your blue line above everyone else. Generally the quickest way to do this is to race to weapons->phasers, and crank out fighters. Those fighters raise your military rating and therefore make you less of a target. Since the AI will no longer attack you, you're free to do what you want to do until you wish to initiate a war.

Mind your economic sliders... judicious use of them can make or break you.

SeanB