Rather than take away the playstation can you just give him time out and see if this works better. It might make him less angry and it give the child some time to think about the behaviour.
My daughter is only 2 but I was having terrible problems with her, tantrums and aggression mainly. I cut out preservative 282 which is found in some breads, crumpets, refridgerated pasta. It took about a week to work but I saw a huge improvement in her behaviour so it might be worth a try.
I have the same lip from my 9 year old too. Lots of 'whatever', 'bothered' etc!! My son is an angel as a rule and i am forever complimented on his behaviour. Back at home, life is rather different. If i tell him to go to his room he just says 'make me'. Nightmare! Don't know how to respond to this at all.
I have threatened to take him to the head teacher the next morning or the doctor as his behaviour is unreasonable and mummy needs help. This plays on his conscience for a while.
Not much help i'm afraid but at least you know someone else is suffering!!!