It represents hw epic teh graphix are. You can neva argue dat ur pushn da system toits limits if ya dnt skip sum frams.

The campaign enviornments and cutscenes have a lot more going on than the multiplayer modes.

I didn't notice.  Let me say this, though:  The graphics weren't the end all/be all that I expected.  I was far from blown away but I only logged in an hour.  I expect things to pick up, soon enough.  The immersive music I expect from a Halo wasn't there just yet, either.  I did see it pause for a milli-second when the game "Reach"-ed chech points but no.  Never saw the frame rate chug.  I install every game I play so maybe that's the reason.  I dunno.

Like I posted elsewhere, the game hasn't hooked me just yet (keep in mind I'm not a big FPS fan and the only reason I got it on day one is because my co-op partner got it on day one) but I can recognize quality when I see it.  This game oozes quality.  But if it has frame issues, then so be it.  "It is what it is."

I have only noticed chugs during the cut scenes.  Then again, I am only 4 mission deep, so maybe it gets worse as you go.

i played halo 3 with my surround headset and was blown away while in halo reach i never had that feeling besides that screen of stars once you start up the disc

In cutscenes maybe 28FPS sometimes , but I haven't experienced even 1 framerate drop in the whole campaign even though there were like 10 explosions going on at the same time at one point.

like i said i have a video if you want proof. there were about 10 hiccups in it

Doesn't have to be a game problem though. Disc or drive could have been to slow for example.

it always happens in open environment or when there are a million banshees flying around

I've played through the campaign three times and I got maybe 2 occasions each time where it actually paused for a split second.  While playing online coop I had one game where it was lagging badly but that could have been connection issues with the host.  I have seen the odd dropped frame on cutscenes too but it's rare in my experience and not at any particulr point in time everytime.  Other than that for the hours I've played it it's been rock solid so I'd say you have an issue if it's doing it all the time.  Perhaps you should try flushing the cache on your HDD OP.