Well like 4 weeks ago my system got the rrod.so i procrastinated and waited until today October 11, to send it in.. i was wondering how long would it take to be sent back..i pre-ordered Call of Duty Modern Warfare 2 and i don’t want to get my 360 back after the game comes out..i live in New Jersey so how long

It usually takes anywhere from 5 to 14 days to get it back. That is not a guarantee, just a normal timeframe. You SHOULD have it back in time for the COD:MW2 release.
Good Luck
Honestly, sending an Xbox to Microsoft can take up to 3-6 weeks depending on where you are located. Generally I advise people to just do a quick 3 red lights fix themselves and save the hassle.