i have an integrated graphix "extreme", and let me tell you, there is nothing 'extreme' about it, except for maybe the degree of crappy graphix it brings
i can't see textures, but only the basic color of the texture which happens to be different for every 50 square feet.
i can only see a few select flames from the flame thrower, the plasma grenade leaves a blue blotch on my screen (what was once a beutiful effect is now a horrible sprite made up of one color) and i can't see muzzle flashes, decals (like blood and bullet holes), or the actual color the spartans are!
and what makes things WORSE is the fact that the pc i'm using is so full of viruses, spyware, ad-aware, malware and generic company unwanted software, that a portion of my clock cycles per second is devoted to these unwanted applications, causing a significant slowdown once each second, for about a quarter of a second. and then there's the fact that every 5-10 minutes, a firefox window opens up, making me exit from halo to the desktop (and sometimes for no reason!)
and yet i still kick serious ass in every case
all-in-all, avoid relying on built-in graphix over an actual card whenever you can