question:
when my car is on and at a stop light (w/the air on, radio off), it feels like something is rattling in the engine...also, when i'm cruisin' down the interstate w/all the windows up, it sounds like there is a whole lotta air coming in....does anyone else have this problem?

 

Are cars seem to have fairly aggressive venilation systems. THis is nice in some respects as you don't have to have the fan running at highway speeds to heat the car, (the a/c turns off when the fan is off.) I've found this to be common with many mazda cars.
Does the rattle come when the car is warming up? This is a pretty common problem also but there's nothing wrong with the car. I'm not sure what else could be causing the rattling other than maybe a lifter? or just a rough idle setting. Have you changed your spark plugs lately? Sometimes a loose plug wire will cause a rattling sound also.

 

it rattles a lil' when i start the car up, but its mainly when i got the a/c on...i got my 30k maintance...but they didnt change the spark plugs...i got the car in oct 02.