How can i avoid lag in Black Ops Xbox?

YES. if you shutdown running programs in the background on your computer off this will help. i dont mean the minimized internet i mean background programms that are hidden. next you can not download anything while playing black ops, like on utorrent. i know you said you arent but if you are that reduces your kb. next try shutting down your router everynight. this gives it a rest and lets it run at maximum power. and lastly if your ps3 is close to your computer use a cord to plug it in and you should get 3/3 bars