Instant Warranty?

I just bought an Xbox 360 do I need to register to get the Microsoft 1 year warranty, or do I alrerady have the warranty for 1 year.

when mine broke the microsoft guy said every xbox 360 is under warranty aslong as its not tamperd with i didnt register mine the guy also implied that no matter how old it is theyll fix it so i dont understand wot that 1 year warranty is about, this is from england not the states dunno if its diffrent there.