Ah Claudius. I have been there myself. Don't sweat it. Just call Xbox and they will set up how you are to get another one free. it's a refurb, but hey - it'll be fine. I did this last summer and it surprisingly took pretty quick. less than 2 weeks in total. Just like Jumpman said. My refurb has been totally fine. It's a little loud, but who cares - they'll just give me another one for free if this one breaks again.
Mine was like 3 years old and wasn't registered. When i called microsoft i told them i got it as a gift and they just registered it for me over the phone.
Anyways, Microsoft actually is being really good about the whole thing.
Personally when it happened to me, i was really pissed off and highly considered getting a PS3 (as per Benzo's harsh advise at the time). However, having to buy my favorite games AND the system would end up costing something like $500+ . what for!? Just go some time without your console and get another free one.
I'm sure you are really pissed now. I was when it happened to me... you'll be alright.